s/sout_stream_id_t/sout_stream_id_sys_t/

[vlc.git] / modules / stream_out / rtpfmt.c

/*****************************************************************************
 * rtpfmt.c: RTP payload formats
 *****************************************************************************
 * Copyright (C) 2003-2004 VLC authors and VideoLAN
 * Copyright © 2007 Rémi Denis-Courmont
 * $Id$
 *
 * Authors: Laurent Aimar <fenrir@via.ecp.fr>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <vlc_common.h>
#include <vlc_sout.h>
#include <vlc_block.h>
#include <vlc_strings.h>

#include "rtp.h"
#include "../demux/xiph.h"

#include <assert.h>

static int rtp_packetize_mpa  (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_mpv  (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_ac3  (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_split(sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_swab (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_mp4a (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_mp4a_latm (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_h263 (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_h264 (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_amr  (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_spx  (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_t140 (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_g726_16 (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_g726_24 (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_g726_32 (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_g726_40 (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_xiph (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_vp8 (sout_stream_id_sys_t *, block_t *);
static int rtp_packetize_jpeg (sout_stream_id_sys_t *, block_t *);

#define XIPH_IDENT (0)

/* Helpers common to xiph codecs (vorbis and theora) */

static int rtp_xiph_pack_headers(size_t room, void *p_extra, size_t i_extra,
                                 uint8_t **p_buffer, size_t *i_buffer,
                                 uint8_t *theora_pixel_fmt)
{
    unsigned packet_size[XIPH_MAX_HEADER_COUNT];
    void *packet[XIPH_MAX_HEADER_COUNT];
    unsigned packet_count;
    if (xiph_SplitHeaders(packet_size, packet, &packet_count,
                                i_extra, p_extra))
        return VLC_EGENERIC;;
    if (packet_count < 3)
        return VLC_EGENERIC;;

    if (theora_pixel_fmt != NULL)
    {
        if (packet_size[0] < 42)
            return VLC_EGENERIC;
        *theora_pixel_fmt = (((uint8_t *)packet[0])[41] >> 3) & 0x03;
    }

    unsigned length_size[2] = { 0, 0 };
    for (int i = 0; i < 2; i++)
    {
        unsigned size = packet_size[i];
        while (size > 0)
        {
            length_size[i]++;
            size >>= 7;
        }
    }

    *i_buffer = room + 1 + length_size[0] + length_size[1]
                + packet_size[0] + packet_size[1] + packet_size[2];
    *p_buffer = malloc(*i_buffer);
    if (*p_buffer == NULL)
        return VLC_ENOMEM;

    uint8_t *p = *p_buffer + room;
    /* Number of headers */
    *p++ = 2;

    for (int i = 0; i < 2; i++)
    {
        unsigned size = length_size[i];
        while (size > 0)
        {
            *p = (packet_size[i] >> (7 * (size - 1))) & 0x7f;
            if (--size > 0)
                *p |= 0x80;
            p++;
        }
    }
    for (int i = 0; i < 3; i++)
    {
        memcpy(p, packet[i], packet_size[i]);
        p += packet_size[i];
    }

    return VLC_SUCCESS;
}

static char *rtp_xiph_b64_oob_config(void *p_extra, size_t i_extra,
                                     uint8_t *theora_pixel_fmt)
{
    uint8_t *p_buffer;
    size_t i_buffer;
    if (rtp_xiph_pack_headers(9, p_extra, i_extra, &p_buffer, &i_buffer,
                              theora_pixel_fmt) != VLC_SUCCESS)
        return NULL;

    /* Number of packed headers */
    SetDWBE(p_buffer, 1);
    /* Ident */
    uint32_t ident = XIPH_IDENT;
    SetWBE(p_buffer + 4, ident >> 8);
    p_buffer[6] = ident & 0xff;
    /* Length field */
    SetWBE(p_buffer + 7, i_buffer);

    char *config = vlc_b64_encode_binary(p_buffer, i_buffer);
    free(p_buffer);
    return config;
}

static void sprintf_hexa( char *s, uint8_t *p_data, int i_data )
{
    static const char hex[16] = "0123456789abcdef";

    for( int i = 0; i < i_data; i++ )
    {
        s[2*i+0] = hex[(p_data[i]>>4)&0xf];
        s[2*i+1] = hex[(p_data[i]   )&0xf];
    }
    s[2*i_data] = '\0';
}

/* TODO: make this into something more clever than a big switch? */
int rtp_get_fmt( vlc_object_t *obj, es_format_t *p_fmt, const char *mux,
                  rtp_format_t *rtp_fmt )
{
    assert( p_fmt != NULL || mux != NULL );

    /* Dynamic payload type. Payload types are scoped to the RTP
     * session, and we put each ES in its own session, so no risk of
     * conflict. */
    rtp_fmt->payload_type = 96;
    rtp_fmt->cat = mux != NULL ? VIDEO_ES : p_fmt->i_cat;
    if( rtp_fmt->cat == AUDIO_ES )
    {
        rtp_fmt->clock_rate = p_fmt->audio.i_rate;
        rtp_fmt->channels = p_fmt->audio.i_channels;
    }
    else
        rtp_fmt->clock_rate = 90000; /* most common case for video */
    /* Stream bitrate in kbps */
    rtp_fmt->bitrate = p_fmt != NULL ? p_fmt->i_bitrate/1000 : 0;
    rtp_fmt->fmtp = NULL;

    if( mux != NULL )
    {
        if( strncmp( mux, "ts", 2 ) == 0 )
        {
            rtp_fmt->payload_type = 33;
            rtp_fmt->ptname = "MP2T";
        }
        else
            rtp_fmt->ptname = "MP2P";
        return VLC_SUCCESS;
    }

    switch( p_fmt->i_codec )
    {
        case VLC_CODEC_MULAW:
            if( p_fmt->audio.i_channels == 1 && p_fmt->audio.i_rate == 8000 )
                rtp_fmt->payload_type = 0;
            rtp_fmt->ptname = "PCMU";
            rtp_fmt->pf_packetize = rtp_packetize_split;
            break;
        case VLC_CODEC_ALAW:
            if( p_fmt->audio.i_channels == 1 && p_fmt->audio.i_rate == 8000 )
                rtp_fmt->payload_type = 8;
            rtp_fmt->ptname = "PCMA";
            rtp_fmt->pf_packetize = rtp_packetize_split;
            break;
        case VLC_CODEC_S16B:
        case VLC_CODEC_S16L:
            if( p_fmt->audio.i_channels == 1 && p_fmt->audio.i_rate == 44100 )
            {
                rtp_fmt->payload_type = 11;
            }
            else if( p_fmt->audio.i_channels == 2 &&
                     p_fmt->audio.i_rate == 44100 )
            {
                rtp_fmt->payload_type = 10;
            }
            rtp_fmt->ptname = "L16";
            if( p_fmt->i_codec == VLC_CODEC_S16B )
                rtp_fmt->pf_packetize = rtp_packetize_split;
            else
                rtp_fmt->pf_packetize = rtp_packetize_swab;
            break;
        case VLC_CODEC_U8:
            rtp_fmt->ptname = "L8";
            rtp_fmt->pf_packetize = rtp_packetize_split;
            break;
        case VLC_CODEC_S24B:
            rtp_fmt->ptname = "L24";
            rtp_fmt->pf_packetize = rtp_packetize_split;
            break;
        case VLC_CODEC_MPGA:
            rtp_fmt->payload_type = 14;
            rtp_fmt->ptname = "MPA";
            rtp_fmt->clock_rate = 90000; /* not 44100 */
            rtp_fmt->pf_packetize = rtp_packetize_mpa;
            break;
        case VLC_CODEC_MPGV:
            rtp_fmt->payload_type = 32;
            rtp_fmt->ptname = "MPV";
            rtp_fmt->pf_packetize = rtp_packetize_mpv;
            break;
        case VLC_CODEC_ADPCM_G726:
            switch( p_fmt->i_bitrate / 1000 )
            {
            case 16:
                rtp_fmt->ptname = "G726-16";
                rtp_fmt->pf_packetize = rtp_packetize_g726_16;
                break;
            case 24:
                rtp_fmt->ptname = "G726-24";
                rtp_fmt->pf_packetize = rtp_packetize_g726_24;
                break;
            case 32:
                rtp_fmt->ptname = "G726-32";
                rtp_fmt->pf_packetize = rtp_packetize_g726_32;
                break;
            case 40:
                rtp_fmt->ptname = "G726-40";
                rtp_fmt->pf_packetize = rtp_packetize_g726_40;
                break;
            default:
                msg_Err( obj, "cannot add this stream (unsupported "
                         "G.726 bit rate: %u)", p_fmt->i_bitrate );
                return VLC_EGENERIC;
            }
            break;
        case VLC_CODEC_A52:
            rtp_fmt->ptname = "ac3";
            rtp_fmt->pf_packetize = rtp_packetize_ac3;
            break;
        case VLC_CODEC_H263:
            rtp_fmt->ptname = "H263-1998";
            rtp_fmt->pf_packetize = rtp_packetize_h263;
            break;
        case VLC_CODEC_H264:
            rtp_fmt->ptname = "H264";
            rtp_fmt->pf_packetize = rtp_packetize_h264;
            rtp_fmt->fmtp = NULL;

            if( p_fmt->i_extra > 0 )
            {
                uint8_t *p_buffer = p_fmt->p_extra;
                int     i_buffer = p_fmt->i_extra;
                char    *p_64_sps = NULL;
                char    *p_64_pps = NULL;
                char    hexa[6+1];

                while( i_buffer > 4 )
                {
                    int i_offset    = 0;
                    int i_size      = 0;

                    while( p_buffer[0] != 0 || p_buffer[1] != 0 ||
                           p_buffer[2] != 1 )
                    {
                        p_buffer++;
                        i_buffer--;
                        if( i_buffer == 0 ) break;
                    }

                    if( i_buffer < 4 || memcmp(p_buffer, "\x00\x00\x01", 3 ) )
                    {
                        msg_Dbg( obj, "No startcode found..");
                        break;
                    }
                    p_buffer += 3;
                    i_buffer -= 3;

                    const int i_nal_type = p_buffer[0]&0x1f;

                    msg_Dbg( obj, "we found a startcode for NAL with TYPE:%d", i_nal_type );

                    i_size = i_buffer;
                    for( i_offset = 0; i_offset+2 < i_buffer ; i_offset++)
                    {
                        if( !memcmp(p_buffer + i_offset, "\x00\x00\x01", 3 ) )
                        {
                            /* we found another startcode */
                            while( i_offset > 0 && 0 == p_buffer[ i_offset - 1 ] )
                                i_offset--;
                            i_size = i_offset;
                            break;
                        }
                    }

                    if( i_size == 0 )
                    {
                        msg_Dbg( obj, "No-info found in nal ");
                        continue;
                    }

                    if( i_nal_type == 7 )
                    {
                        free( p_64_sps );
                        p_64_sps = vlc_b64_encode_binary( p_buffer, i_size );
                        /* XXX: nothing ensures that i_size >= 4 ?? */
                        sprintf_hexa( hexa, &p_buffer[1], 3 );
                    }
                    else if( i_nal_type == 8 )
                    {
                        free( p_64_pps );
                        p_64_pps = vlc_b64_encode_binary( p_buffer, i_size );
                    }
                    i_buffer -= i_size;
                    p_buffer += i_size;
                }
                /* */
                if( p_64_sps && p_64_pps &&
                    ( asprintf( &rtp_fmt->fmtp,
                                "packetization-mode=1;profile-level-id=%s;"
                                "sprop-parameter-sets=%s,%s;", hexa, p_64_sps,
                                p_64_pps ) == -1 ) )
                    rtp_fmt->fmtp = NULL;
                free( p_64_sps );
                free( p_64_pps );
            }
            if( rtp_fmt->fmtp == NULL )
                rtp_fmt->fmtp = strdup( "packetization-mode=1" );
            break;

        case VLC_CODEC_MP4V:
        {
            rtp_fmt->ptname = "MP4V-ES";
            rtp_fmt->pf_packetize = rtp_packetize_split;
            if( p_fmt->i_extra > 0 )
            {
                char hexa[2*p_fmt->i_extra +1];
                sprintf_hexa( hexa, p_fmt->p_extra, p_fmt->i_extra );
                if( asprintf( &rtp_fmt->fmtp,
                              "profile-level-id=3; config=%s;", hexa ) == -1 )
                    rtp_fmt->fmtp = NULL;
            }
            break;
        }
        case VLC_CODEC_MP4A:
        {
            if( ! var_InheritBool( obj, "sout-rtp-mp4a-latm" ) )
            {
                char hexa[2*p_fmt->i_extra +1];

                rtp_fmt->ptname = "mpeg4-generic";
                rtp_fmt->pf_packetize = rtp_packetize_mp4a;
                sprintf_hexa( hexa, p_fmt->p_extra, p_fmt->i_extra );
                if( asprintf( &rtp_fmt->fmtp,
                              "streamtype=5; profile-level-id=15; "
                              "mode=AAC-hbr; config=%s; SizeLength=13; "
                              "IndexLength=3; IndexDeltaLength=3; Profile=1;",
                              hexa ) == -1 )
                    rtp_fmt->fmtp = NULL;
            }
            else
            {
                char hexa[13];
                int i;
                unsigned char config[6];
                unsigned int aacsrates[15] = {
                    96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050,
                    16000, 12000, 11025, 8000, 7350, 0, 0 };

                for( i = 0; i < 15; i++ )
                    if( p_fmt->audio.i_rate == aacsrates[i] )
                        break;

                config[0]=0x40;
                config[1]=0;
                config[2]=0x20|i;
                config[3]=p_fmt->audio.i_channels<<4;
                config[4]=0x3f;
                config[5]=0xc0;

                rtp_fmt->ptname = "MP4A-LATM";
                rtp_fmt->pf_packetize = rtp_packetize_mp4a_latm;
                sprintf_hexa( hexa, config, 6 );
                if( asprintf( &rtp_fmt->fmtp, "profile-level-id=15; "
                              "object=2; cpresent=0; config=%s", hexa ) == -1 )
                    rtp_fmt->fmtp = NULL;
            }
            break;
        }
        case VLC_CODEC_AMR_NB:
            rtp_fmt->ptname = "AMR";
            rtp_fmt->fmtp = strdup( "octet-align=1" );
            rtp_fmt->pf_packetize = rtp_packetize_amr;
            break;
        case VLC_CODEC_AMR_WB:
            rtp_fmt->ptname = "AMR-WB";
            rtp_fmt->fmtp = strdup( "octet-align=1" );
            rtp_fmt->pf_packetize = rtp_packetize_amr;
            break;
        case VLC_CODEC_SPEEX:
            rtp_fmt->ptname = "SPEEX";
            rtp_fmt->pf_packetize = rtp_packetize_spx;
            break;
        case VLC_CODEC_VORBIS:
            rtp_fmt->ptname = "vorbis";
            rtp_fmt->pf_packetize = rtp_packetize_xiph;
            if( p_fmt->i_extra > 0 )
            {
                rtp_fmt->fmtp = NULL;
                char *config = rtp_xiph_b64_oob_config(p_fmt->p_extra,
                                                       p_fmt->i_extra, NULL);
                if (config == NULL)
                    break;
                if( asprintf( &rtp_fmt->fmtp,
                              "configuration=%s;", config ) == -1 )
                    rtp_fmt->fmtp = NULL;
                free(config);
            }
            break;
        case VLC_CODEC_THEORA:
            rtp_fmt->ptname = "theora";
            rtp_fmt->pf_packetize = rtp_packetize_xiph;
            if( p_fmt->i_extra > 0 )
            {
                rtp_fmt->fmtp = NULL;
                uint8_t pixel_fmt, c1, c2;
                char *config = rtp_xiph_b64_oob_config(p_fmt->p_extra,
                                                       p_fmt->i_extra,
                                                       &pixel_fmt);
                if (config == NULL)
                    break;

                if (pixel_fmt == 1)
                {
                    /* reserved */
                    free(config);
                    break;
                }
                switch (pixel_fmt)
                {
                    case 0:
                        c1 = 2;
                        c2 = 0;
                        break;
                    case 2:
                        c1 = c2 = 2;
                        break;
                    case 3:
                        c1 = c2 = 4;
                        break;
                    default:
                        assert(0);
                }

                if( asprintf( &rtp_fmt->fmtp,
                              "sampling=YCbCr-4:%d:%d; width=%d; height=%d; "
                              "delivery-method=inline; configuration=%s; "
                              "delivery-method=in_band;", c1, c2,
                              p_fmt->video.i_width, p_fmt->video.i_height,
                              config ) == -1 )
                    rtp_fmt->fmtp = NULL;
                free(config);
            }
            break;
        case VLC_CODEC_ITU_T140:
            rtp_fmt->ptname = "t140" ;
            rtp_fmt->clock_rate = 1000;
            rtp_fmt->pf_packetize = rtp_packetize_t140;
            break;
        case VLC_CODEC_GSM:
            rtp_fmt->payload_type = 3;
            rtp_fmt->ptname = "GSM";
            rtp_fmt->pf_packetize = rtp_packetize_split;
            break;
        case VLC_CODEC_OPUS:
            if (p_fmt->audio.i_channels > 2)
            {
                msg_Err( obj, "Multistream opus not supported in RTP"
                         " (having %d channels input)",
                         p_fmt->audio.i_channels );
                return VLC_EGENERIC;
            }
            rtp_fmt->ptname = "opus";
            rtp_fmt->pf_packetize = rtp_packetize_split;
            rtp_fmt->clock_rate = 48000;
            rtp_fmt->channels = 2;
            if (p_fmt->audio.i_channels == 2)
                rtp_fmt->fmtp = strdup( "sprop-stereo=1" );
            break;
        case VLC_CODEC_VP8:
            rtp_fmt->ptname = "VP8";
            rtp_fmt->pf_packetize = rtp_packetize_vp8;
            break;
        case VLC_CODEC_MJPG:
        case VLC_CODEC_JPEG:
            rtp_fmt->ptname = "JPEG";
            rtp_fmt->payload_type = 26;
            rtp_fmt->pf_packetize = rtp_packetize_jpeg;
            break;

        default:
            msg_Err( obj, "cannot add this stream (unsupported "
                     "codec: %4.4s)", (char*)&p_fmt->i_codec );
            return VLC_EGENERIC;
    }

    return VLC_SUCCESS;
}


static int
rtp_packetize_h264_nal( sout_stream_id_sys_t *id,
                        const uint8_t *p_data, int i_data, int64_t i_pts,
                        int64_t i_dts, bool b_last, int64_t i_length );

int rtp_packetize_xiph_config( sout_stream_id_sys_t *id, const char *fmtp,
                               int64_t i_pts )
{
    if (fmtp == NULL)
        return VLC_EGENERIC;

    /* extract base64 configuration from fmtp */
    char *start = strstr(fmtp, "configuration=");
    assert(start != NULL);
    start += sizeof("configuration=") - 1;
    char *end = strchr(start, ';');
    assert(end != NULL);
    size_t len = end - start;
    char b64[len + 1];
    memcpy(b64, start, len);
    b64[len] = '\0';

    int     i_max   = rtp_mtu (id) - 6; /* payload max in one packet */

    uint8_t *p_orig, *p_data;
    int i_data;

    i_data = vlc_b64_decode_binary(&p_orig, b64);
    if (i_data == 0)
        return VLC_EGENERIC;
    assert(i_data > 9);
    p_data = p_orig + 9;
    i_data -= 9;

    int i_count = ( i_data + i_max - 1 ) / i_max;

    for( int i = 0; i < i_count; i++ )
    {
        int           i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( 18 + i_payload );

        unsigned fragtype, numpkts;
        if (i_count == 1)
        {
            fragtype = 0;
            numpkts = 1;
        }
        else
        {
            numpkts = 0;
            if (i == 0)
                fragtype = 1;
            else if (i == i_count - 1)
                fragtype = 3;
            else
                fragtype = 2;
        }
        /* Ident:24, Fragment type:2, Vorbis/Theora Data Type:2, # of pkts:4 */
        uint32_t header = ((XIPH_IDENT & 0xffffff) << 8) |
                          (fragtype << 6) | (1 << 4) | numpkts;

        /* rtp common header */
        rtp_packetize_common( id, out, 0, i_pts );

        SetDWBE( out->p_buffer + 12, header);
        SetWBE( out->p_buffer + 16, i_payload);
        memcpy( &out->p_buffer[18], p_data, i_payload );

        out->i_buffer   = 18 + i_payload;
        out->i_dts    = i_pts;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    free(p_orig);

    return VLC_SUCCESS;
}

/* rfc5215 */
static int rtp_packetize_xiph( sout_stream_id_sys_t *id, block_t *in )
{
    int     i_max   = rtp_mtu (id) - 6; /* payload max in one packet */
    int     i_count = ( in->i_buffer + i_max - 1 ) / i_max;

    uint8_t *p_data = in->p_buffer;
    int     i_data  = in->i_buffer;

    for( int i = 0; i < i_count; i++ )
    {
        int           i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( 18 + i_payload );

        unsigned fragtype, numpkts;
        if (i_count == 1)
        {
            /* No fragmentation */
            fragtype = 0;
            numpkts = 1;
        }
        else
        {
            /* Fragmentation */
            numpkts = 0;
            if (i == 0)
                fragtype = 1;
            else if (i == i_count - 1)
                fragtype = 3;
            else
                fragtype = 2;
        }
        /* Ident:24, Fragment type:2, Vorbis/Theora Data Type:2, # of pkts:4 */
        uint32_t header = ((XIPH_IDENT & 0xffffff) << 8) |
                          (fragtype << 6) | (0 << 4) | numpkts;

        /* rtp common header */
        rtp_packetize_common( id, out, 0, in->i_pts);

        SetDWBE( out->p_buffer + 12, header);
        SetWBE( out->p_buffer + 16, i_payload);
        memcpy( &out->p_buffer[18], p_data, i_payload );

        out->i_buffer   = 18 + i_payload;
        out->i_dts    = in->i_dts + i * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}

static int rtp_packetize_mpa( sout_stream_id_sys_t *id, block_t *in )
{
    int     i_max   = rtp_mtu (id) - 4; /* payload max in one packet */
    int     i_count = ( in->i_buffer + i_max - 1 ) / i_max;

    uint8_t *p_data = in->p_buffer;
    int     i_data  = in->i_buffer;
    int     i;

    for( i = 0; i < i_count; i++ )
    {
        int           i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( 16 + i_payload );

        /* rtp common header */
        rtp_packetize_common( id, out, (i == i_count - 1)?1:0, in->i_pts );
        /* mbz set to 0 */
        SetWBE( out->p_buffer + 12, 0 );
        /* fragment offset in the current frame */
        SetWBE( out->p_buffer + 14, i * i_max );
        memcpy( &out->p_buffer[16], p_data, i_payload );

        out->i_buffer   = 16 + i_payload;
        out->i_dts    = in->i_dts + i * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}

/* rfc2250 */
static int rtp_packetize_mpv( sout_stream_id_sys_t *id, block_t *in )
{
    int     i_max   = rtp_mtu (id) - 4; /* payload max in one packet */
    int     i_count = ( in->i_buffer + i_max - 1 ) / i_max;

    uint8_t *p_data = in->p_buffer;
    int     i_data  = in->i_buffer;
    int     i;
    int     b_sequence_start = 0;
    int     i_temporal_ref = 0;
    int     i_picture_coding_type = 0;
    int     i_fbv = 0, i_bfc = 0, i_ffv = 0, i_ffc = 0;
    int     b_start_slice = 0;

    /* preparse this packet to get some info */
    if( in->i_buffer > 4 )
    {
        uint8_t *p = p_data;
        int      i_rest = in->i_buffer;

        for( ;; )
        {
            while( i_rest > 4 &&
                   ( p[0] != 0x00 || p[1] != 0x00 || p[2] != 0x01 ) )
            {
                p++;
                i_rest--;
            }
            if( i_rest <= 4 )
            {
                break;
            }
            p += 3;
            i_rest -= 4;

            if( *p == 0xb3 )
            {
                /* sequence start code */
                b_sequence_start = 1;
            }
            else if( *p == 0x00 && i_rest >= 4 )
            {
                /* picture */
                i_temporal_ref = ( p[1] << 2) |((p[2]>>6)&0x03);
                i_picture_coding_type = (p[2] >> 3)&0x07;

                if( i_rest >= 4 && ( i_picture_coding_type == 2 ||
                                    i_picture_coding_type == 3 ) )
                {
                    i_ffv = (p[3] >> 2)&0x01;
                    i_ffc = ((p[3]&0x03) << 1)|((p[4]>>7)&0x01);
                    if( i_rest > 4 && i_picture_coding_type == 3 )
                    {
                        i_fbv = (p[4]>>6)&0x01;
                        i_bfc = (p[4]>>3)&0x07;
                    }
                }
            }
            else if( *p <= 0xaf )
            {
                b_start_slice = 1;
            }
        }
    }

    for( i = 0; i < i_count; i++ )
    {
        int           i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( 16 + i_payload );
        /* MBZ:5 T:1 TR:10 AN:1 N:1 S:1 B:1 E:1 P:3 FBV:1 BFC:3 FFV:1 FFC:3 */
        uint32_t      h = ( i_temporal_ref << 16 )|
                          ( b_sequence_start << 13 )|
                          ( b_start_slice << 12 )|
                          ( i == i_count - 1 ? 1 << 11 : 0 )|
                          ( i_picture_coding_type << 8 )|
                          ( i_fbv << 7 )|( i_bfc << 4 )|( i_ffv << 3 )|i_ffc;

        /* rtp common header */
        rtp_packetize_common( id, out, (i == i_count - 1)?1:0,
                          in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts );

        SetDWBE( out->p_buffer + 12, h );

        memcpy( &out->p_buffer[16], p_data, i_payload );

        out->i_buffer   = 16 + i_payload;
        out->i_dts    = in->i_dts + i * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}

static int rtp_packetize_ac3( sout_stream_id_sys_t *id, block_t *in )
{
    int     i_max   = rtp_mtu (id) - 2; /* payload max in one packet */
    int     i_count = ( in->i_buffer + i_max - 1 ) / i_max;

    uint8_t *p_data = in->p_buffer;
    int     i_data  = in->i_buffer;
    int     i;

    for( i = 0; i < i_count; i++ )
    {
        int           i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( 14 + i_payload );

        /* rtp common header */
        rtp_packetize_common( id, out, (i == i_count - 1)?1:0, in->i_pts );
        /* unit count */
        out->p_buffer[12] = 1;
        /* unit header */
        out->p_buffer[13] = 0x00;
        /* data */
        memcpy( &out->p_buffer[14], p_data, i_payload );

        out->i_buffer   = 14 + i_payload;
        out->i_dts    = in->i_dts + i * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}

static int rtp_packetize_split( sout_stream_id_sys_t *id, block_t *in )
{
    int     i_max   = rtp_mtu (id); /* payload max in one packet */
    int     i_count = ( in->i_buffer + i_max - 1 ) / i_max;

    uint8_t *p_data = in->p_buffer;
    int     i_data  = in->i_buffer;
    int     i;

    for( i = 0; i < i_count; i++ )
    {
        int           i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( 12 + i_payload );

        /* rtp common header */
        rtp_packetize_common( id, out, (i == i_count - 1),
                      (in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts) );
        memcpy( &out->p_buffer[12], p_data, i_payload );

        out->i_buffer   = 12 + i_payload;
        out->i_dts    = in->i_dts + i * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}

/* split and convert from little endian to network byte order */
static int rtp_packetize_swab( sout_stream_id_sys_t *id, block_t *in )
{
    int     i_max   = rtp_mtu (id); /* payload max in one packet */
    int     i_count = ( in->i_buffer + i_max - 1 ) / i_max;

    uint8_t *p_data = in->p_buffer;
    int     i_data  = in->i_buffer;
    int     i;

    for( i = 0; i < i_count; i++ )
    {
        int           i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( 12 + i_payload );

        /* rtp common header */
        rtp_packetize_common( id, out, (i == i_count - 1),
                      (in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts) );
        swab( p_data, out->p_buffer + 12, i_payload );

        out->i_buffer = 12 + i_payload;
        out->i_dts    = in->i_dts + i * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}

/* rfc3016 */
static int rtp_packetize_mp4a_latm( sout_stream_id_sys_t *id, block_t *in )
{
    int     i_max   = rtp_mtu (id) - 2;              /* payload max in one packet */
    int     latmhdrsize = in->i_buffer / 0xff + 1;
    int     i_count = ( in->i_buffer + i_max - 1 ) / i_max;

    uint8_t *p_data = in->p_buffer, *p_header = NULL;
    int     i_data  = in->i_buffer;
    int     i;

    for( i = 0; i < i_count; i++ )
    {
        int     i_payload = __MIN( i_max, i_data );
        block_t *out;

        if( i != 0 )
            latmhdrsize = 0;
        out = block_Alloc( 12 + latmhdrsize + i_payload );

        /* rtp common header */
        rtp_packetize_common( id, out, ((i == i_count - 1) ? 1 : 0),
                      (in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts) );

        if( i == 0 )
        {
            int tmp = in->i_buffer;

            p_header=out->p_buffer+12;
            while( tmp > 0xfe )
            {
                *p_header = 0xff;
                p_header++;
                tmp -= 0xff;
            }
            *p_header = tmp;
        }

        memcpy( &out->p_buffer[12+latmhdrsize], p_data, i_payload );

        out->i_buffer   = 12 + latmhdrsize + i_payload;
        out->i_dts    = in->i_dts + i * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}

static int rtp_packetize_mp4a( sout_stream_id_sys_t *id, block_t *in )
{
    int     i_max   = rtp_mtu (id) - 4; /* payload max in one packet */
    int     i_count = ( in->i_buffer + i_max - 1 ) / i_max;

    uint8_t *p_data = in->p_buffer;
    int     i_data  = in->i_buffer;
    int     i;

    for( i = 0; i < i_count; i++ )
    {
        int           i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( 16 + i_payload );

        /* rtp common header */
        rtp_packetize_common( id, out, ((i == i_count - 1)?1:0),
                      (in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts) );
        /* AU headers */
        /* AU headers length (bits) */
        out->p_buffer[12] = 0;
        out->p_buffer[13] = 2*8;
        /* for each AU length 13 bits + idx 3bits, */
        SetWBE( out->p_buffer + 14, (in->i_buffer << 3) | 0 );

        memcpy( &out->p_buffer[16], p_data, i_payload );

        out->i_buffer   = 16 + i_payload;
        out->i_dts    = in->i_dts + i * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}


/* rfc2429 */
#define RTP_H263_HEADER_SIZE (2)  // plen = 0
#define RTP_H263_PAYLOAD_START (14)  // plen = 0
static int rtp_packetize_h263( sout_stream_id_sys_t *id, block_t *in )
{
    uint8_t *p_data = in->p_buffer;
    int     i_data  = in->i_buffer;
    int     i;
    int     i_max   = rtp_mtu (id) - RTP_H263_HEADER_SIZE; /* payload max in one packet */
    int     i_count;
    int     b_p_bit;
    int     b_v_bit = 0; // no pesky error resilience
    int     i_plen = 0; // normally plen=0 for PSC packet
    int     i_pebit = 0; // because plen=0
    uint16_t h;

    if( i_data < 2 )
    {
        return VLC_EGENERIC;
    }
    if( p_data[0] || p_data[1] )
    {
        return VLC_EGENERIC;
    }
    /* remove 2 leading 0 bytes */
    p_data += 2;
    i_data -= 2;
    i_count = ( i_data + i_max - 1 ) / i_max;

    for( i = 0; i < i_count; i++ )
    {
        int      i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( RTP_H263_PAYLOAD_START + i_payload );
        b_p_bit = (i == 0) ? 1 : 0;
        h = ( b_p_bit << 10 )|
            ( b_v_bit << 9  )|
            ( i_plen  << 3  )|
              i_pebit;

        /* rtp common header */
        //b_m_bit = 1; // always contains end of frame
        rtp_packetize_common( id, out, (i == i_count - 1)?1:0,
                          in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts );

        /* h263 header */
        SetWBE( out->p_buffer + 12, h );
        memcpy( &out->p_buffer[RTP_H263_PAYLOAD_START], p_data, i_payload );

        out->i_buffer = RTP_H263_PAYLOAD_START + i_payload;
        out->i_dts    = in->i_dts + i * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}

/* rfc3984 */
static int
rtp_packetize_h264_nal( sout_stream_id_sys_t *id,
                        const uint8_t *p_data, int i_data, int64_t i_pts,
                        int64_t i_dts, bool b_last, int64_t i_length )
{
    const int i_max = rtp_mtu (id); /* payload max in one packet */
    int i_nal_hdr;
    int i_nal_type;

    if( i_data < 5 )
        return VLC_SUCCESS;

    i_nal_hdr = p_data[3];
    i_nal_type = i_nal_hdr&0x1f;

    /* Skip start code */
    p_data += 3;
    i_data -= 3;

    /* */
    if( i_data <= i_max )
    {
        /* Single NAL unit packet */
        block_t *out = block_Alloc( 12 + i_data );
        out->i_dts    = i_dts;
        out->i_length = i_length;

        /* */
        rtp_packetize_common( id, out, b_last, i_pts );
        out->i_buffer = 12 + i_data;

        memcpy( &out->p_buffer[12], p_data, i_data );

        rtp_packetize_send( id, out );
    }
    else
    {
        /* FU-A Fragmentation Unit without interleaving */
        const int i_count = ( i_data-1 + i_max-2 - 1 ) / (i_max-2);
        int i;

        p_data++;
        i_data--;

        for( i = 0; i < i_count; i++ )
        {
            const int i_payload = __MIN( i_data, i_max-2 );
            block_t *out = block_Alloc( 12 + 2 + i_payload );
            out->i_dts    = i_dts + i * i_length / i_count;
            out->i_length = i_length / i_count;

            /* */
            rtp_packetize_common( id, out, (b_last && i_payload == i_data),
                                    i_pts );
            out->i_buffer = 14 + i_payload;

            /* FU indicator */
            out->p_buffer[12] = 0x00 | (i_nal_hdr & 0x60) | 28;
            /* FU header */
            out->p_buffer[13] = ( i == 0 ? 0x80 : 0x00 ) | ( (i == i_count-1) ? 0x40 : 0x00 )  | i_nal_type;
            memcpy( &out->p_buffer[14], p_data, i_payload );

            rtp_packetize_send( id, out );

            i_data -= i_payload;
            p_data += i_payload;
        }
    }
    return VLC_SUCCESS;
}

static int rtp_packetize_h264( sout_stream_id_sys_t *id, block_t *in )
{
    const uint8_t *p_buffer = in->p_buffer;
    int i_buffer = in->i_buffer;

    while( i_buffer > 4 && ( p_buffer[0] != 0 || p_buffer[1] != 0 || p_buffer[2] != 1 ) )
    {
        i_buffer--;
        p_buffer++;
    }

    /* Split nal units */
    while( i_buffer > 4 )
    {
        int i_offset;
        int i_size = i_buffer;
        int i_skip = i_buffer;

        /* search nal end */
        for( i_offset = 4; i_offset+2 < i_buffer ; i_offset++)
        {
            if( p_buffer[i_offset] == 0 && p_buffer[i_offset+1] == 0 && p_buffer[i_offset+2] == 1 )
            {
                /* we found another startcode */
                i_size = i_offset - ( p_buffer[i_offset-1] == 0 ? 1 : 0);
                i_skip = i_offset;
                break;
            }
        }
        /* TODO add STAP-A to remove a lot of overhead with small slice/sei/... */
        rtp_packetize_h264_nal( id, p_buffer, i_size,
                (in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts), in->i_dts,
                (i_size >= i_buffer), in->i_length * i_size / in->i_buffer );

        i_buffer -= i_skip;
        p_buffer += i_skip;
    }
    return VLC_SUCCESS;
}

static int rtp_packetize_amr( sout_stream_id_sys_t *id, block_t *in )
{
    int     i_max   = rtp_mtu (id) - 2; /* payload max in one packet */
    int     i_count = ( in->i_buffer + i_max - 1 ) / i_max;

    uint8_t *p_data = in->p_buffer;
    int     i_data  = in->i_buffer;
    int     i;

    /* Only supports octet-aligned mode */
    for( i = 0; i < i_count; i++ )
    {
        int           i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( 14 + i_payload );

        /* rtp common header */
        rtp_packetize_common( id, out, ((i == i_count - 1)?1:0),
                      (in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts) );
        /* Payload header */
        out->p_buffer[12] = 0xF0; /* CMR */
        out->p_buffer[13] = p_data[0]&0x7C; /* ToC */ /* FIXME: frame type */

        /* FIXME: are we fed multiple frames ? */
        memcpy( &out->p_buffer[14], p_data+1, i_payload-1 );

        out->i_buffer   = 14 + i_payload-1;
        out->i_dts    = in->i_dts + i * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}

static int rtp_packetize_t140( sout_stream_id_sys_t *id, block_t *in )
{
    const size_t   i_max  = rtp_mtu (id);
    const uint8_t *p_data = in->p_buffer;
    size_t         i_data = in->i_buffer;

    for( unsigned i_packet = 0; i_data > 0; i_packet++ )
    {
        size_t i_payload = i_data;

        /* Make sure we stop on an UTF-8 character boundary
         * (assuming the input is valid UTF-8) */
        if( i_data > i_max )
        {
            i_payload = i_max;

            while( ( p_data[i_payload] & 0xC0 ) == 0x80 )
            {
                if( i_payload == 0 )
                    return VLC_SUCCESS; /* fishy input! */

                i_payload--;
            }
        }

        block_t *out = block_Alloc( 12 + i_payload );
        if( out == NULL )
            return VLC_SUCCESS;

        rtp_packetize_common( id, out, 0, in->i_pts + i_packet );
        memcpy( out->p_buffer + 12, p_data, i_payload );

        out->i_buffer = 12 + i_payload;
        out->i_dts    = in->i_pts;
        out->i_length = 0;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}


static int rtp_packetize_spx( sout_stream_id_sys_t *id, block_t *in )
{
    uint8_t *p_buffer = in->p_buffer;
    int i_data_size, i_payload_size, i_payload_padding;
    i_data_size = i_payload_size = in->i_buffer;
    i_payload_padding = 0;
    block_t *p_out;

    if ( in->i_buffer > rtp_mtu (id) )
        return VLC_SUCCESS;

    /*
      RFC for Speex in RTP says that each packet must end on an octet 
      boundary. So, we check to see if the number of bytes % 4 is zero.
      If not, we have to add some padding. 

      This MAY be overkill since packetization is handled elsewhere and 
      appears to ensure the octet boundary. However, better safe than
      sorry.
    */
    if ( i_payload_size % 4 )
    {
        i_payload_padding = 4 - ( i_payload_size % 4 );
        i_payload_size += i_payload_padding;
    }

    /*
      Allocate a new RTP p_output block of the appropriate size. 
      Allow for 12 extra bytes of RTP header. 
    */
    p_out = block_Alloc( 12 + i_payload_size );

    if ( i_payload_padding )
    {
    /*
      The padding is required to be a zero followed by all 1s.
    */
        char c_first_pad, c_remaining_pad;
        c_first_pad = 0x7F;
        c_remaining_pad = 0xFF;

        /*
          Allow for 12 bytes before the i_data_size because
          of the expected RTP header added during
          rtp_packetize_common.
        */
        p_out->p_buffer[12 + i_data_size] = c_first_pad; 
        switch (i_payload_padding)
        {
          case 2:
            p_out->p_buffer[12 + i_data_size + 1] = c_remaining_pad; 
            break;
          case 3:
            p_out->p_buffer[12 + i_data_size + 1] = c_remaining_pad; 
            p_out->p_buffer[12 + i_data_size + 2] = c_remaining_pad; 
            break;
        }
    }

    /* Add the RTP header to our p_output buffer. */
    rtp_packetize_common( id, p_out, 0,
                        (in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts) );
    /* Copy the Speex payload to the p_output buffer */
    memcpy( &p_out->p_buffer[12], p_buffer, i_data_size );

    p_out->i_buffer = 12 + i_payload_size;
    p_out->i_dts = in->i_dts;
    p_out->i_length = in->i_length;

    /* Queue the buffer for actual transmission. */
    rtp_packetize_send( id, p_out );
    return VLC_SUCCESS;
}

static int rtp_packetize_g726( sout_stream_id_sys_t *id, block_t *in, int i_pad )
{
    int     i_max   = (rtp_mtu( id )- 12 + i_pad - 1) & ~i_pad;
    int     i_count = ( in->i_buffer + i_max - 1 ) / i_max;

    uint8_t *p_data = in->p_buffer;
    int     i_data  = in->i_buffer;
    int     i_packet = 0;

    while( i_data > 0 )
    {
        int           i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( 12 + i_payload );

        /* rtp common header */
        rtp_packetize_common( id, out, 0,
                      (in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts) );

        memcpy( &out->p_buffer[12], p_data, i_payload );

        out->i_buffer   = 12 + i_payload;
        out->i_dts    = in->i_dts + i_packet++ * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }
    return VLC_SUCCESS;
}

static int rtp_packetize_g726_16( sout_stream_id_sys_t *id, block_t *in )
{
    return rtp_packetize_g726( id, in, 4 );
}

static int rtp_packetize_g726_24( sout_stream_id_sys_t *id, block_t *in )
{
    return rtp_packetize_g726( id, in, 8 );
}

static int rtp_packetize_g726_32( sout_stream_id_sys_t *id, block_t *in )
{
    return rtp_packetize_g726( id, in, 2 );
}

static int rtp_packetize_g726_40( sout_stream_id_sys_t *id, block_t *in )
{
    return rtp_packetize_g726( id, in, 8 );
}

#define RTP_VP8_HEADER_SIZE 1
#define RTP_VP8_PAYLOAD_START (12 + RTP_VP8_HEADER_SIZE)

static int rtp_packetize_vp8( sout_stream_id_sys_t *id, block_t *in )
{
    int     i_max   = rtp_mtu (id) - RTP_VP8_HEADER_SIZE;
    int     i_count = ( in->i_buffer + i_max - 1 ) / i_max;

    uint8_t *p_data = in->p_buffer;
    int     i_data  = in->i_buffer;

    if ( i_max <= 0 )
        return VLC_EGENERIC;

    for( int i = 0; i < i_count; i++ )
    {
        int i_payload = __MIN( i_max, i_data );
        block_t *out = block_Alloc( RTP_VP8_PAYLOAD_START + i_payload );
        if ( out == NULL )
            return VLC_ENOMEM;

        /* VP8 payload header */
        /* All frames are marked as reference ones */
        if (i == 0)
            out->p_buffer[12] = 0x10; // partition start
        else
            out->p_buffer[12] = 0;

        /* rtp common header */
        rtp_packetize_common( id, out, (i == i_count - 1),
                      (in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts) );
        memcpy( &out->p_buffer[RTP_VP8_PAYLOAD_START], p_data, i_payload );

        out->i_buffer = RTP_VP8_PAYLOAD_START + i_payload;
        out->i_dts    = in->i_dts + i * in->i_length / i_count;
        out->i_length = in->i_length / i_count;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
    }

    return VLC_SUCCESS;
}

static int rtp_packetize_jpeg( sout_stream_id_sys_t *id, block_t *in )
{
    uint8_t *p_data = in->p_buffer;
    int      i_data = in->i_buffer;
    uint8_t *bufend = p_data + i_data;

    const uint8_t *qtables = NULL;
    int nb_qtables = 0;
    int off = 0; // fragment offset in frame
    int y_sampling_factor;
    // type is set by pixel format (determined by y_sampling_factor):
    // 0 for yuvj422p
    // 1 for yuvj420p
    // += 64 if DRI present
    int type;
    int w = 0; // Width in multiples of 8
    int h = 0; // Height in multiples of 8
    int restart_interval;
    int dri_found = 0;

    // Skip SOI
    if (GetWBE(p_data) != 0xffd8)
        return VLC_EGENERIC;
    p_data += 2;
    i_data -= 2;

    /* parse the header to get necessary info */
    int header_finished = 0;
    while (!header_finished && p_data + 4 <= bufend) {
        uint16_t marker = GetWBE(p_data);
        uint8_t *section = p_data + 2;
        int section_size = GetWBE(section);
        uint8_t *section_body = p_data + 4;
        if (section + section_size > bufend)
            return VLC_EGENERIC;

        assert((marker & 0xff00) == 0xff00);
        switch (marker)
        {
            case 0xffdb /*DQT*/:
                if (section_body[0])
                {
                    // Only 8-bit precision is supported
                    return VLC_EGENERIC;
                }

                /* a quantization table is 64 bytes long */
                nb_qtables = section_size / 65;
                qtables = section_body;
                break;
            case 0xffc0 /*SOF0*/:
            {
                int height = GetWBE(&section_body[1]);
                int width = GetWBE(&section_body[3]);
                if (width > 2040 || height > 2040)
                {
                    // larger than limit supported by RFC 2435
                    return VLC_EGENERIC;
                }
                // Round up by 8, divide by 8
                w = ((width+7)&~7) >> 3;
                h = ((height+7)&~7) >> 3;

                // Get components sampling to determine type
                // Y has component ID 1
                // Possible configurations of sampling factors:
                // Y - 0x22, Cb - 0x11, Cr - 0x11 => yuvj420p
                // Y - 0x21, Cb - 0x11, Cr - 0x11 => yuvj422p

                // Only 3 components are supported by RFC 2435
                if (section_body[5] != 3) // Number of components
                    return VLC_EGENERIC;
                for (int j = 0; j < 3; j++)
                {
                    if (section_body[6 + j * 3] == 1 /* Y */)
                    {
                        y_sampling_factor = section_body[6 + j * 3 + 1];
                    }
                    else if (section_body[6 + j * 3 + 1] != 0x11)
                    {
                        // Sampling factor is unsupported by RFC 2435
                        return VLC_EGENERIC;
                    }
                }
                break;
            }
            case 0xffdd /*DRI*/:
                restart_interval = GetWBE(section_body);
                dri_found = 1;
                break;
            case 0xffda /*SOS*/:
                /* SOS is last marker in the header */
                header_finished = 1;
                break;
        }
        // Step over marker, 16bit length and section body
        p_data += 2 + section_size;
        i_data -= 2 + section_size;
    }
    if (!header_finished)
        return VLC_EGENERIC;
    if (!w || !h)
        return VLC_EGENERIC;

    switch (y_sampling_factor)
    {
        case 0x22: // yuvj420p
            type = 1;
            break;
        case 0x21: // yuvj422p
            type = 0;
            break;
        default:
            // Sampling format unsupported by RFC 2435
            return VLC_EGENERIC;
    }

    if (dri_found)
        type += 64;

    while ( i_data )
    {
        int hdr_size = 8 + dri_found * 4;
        if (off == 0 && nb_qtables)
            hdr_size += 4 + 64 * nb_qtables;

        int i_payload = __MIN( i_data, (int)(rtp_mtu (id) - hdr_size) );
        if ( i_payload <= 0 )
            return VLC_EGENERIC;

        block_t *out = block_Alloc( 12 + hdr_size + i_payload );
        if( out == NULL )
            return VLC_ENOMEM;

        uint8_t *p = out->p_buffer + 12;
        /* set main header */
        /* set type-specific=0, set offset in following 24 bits: */
        SetDWBE(p, off & 0x00ffffff);
        p += 4;
        *p++ = type;
        *p++ = 255;  // Quant value
        *p++ = w;
        *p++ = h;

        // Write restart_marker_hdr if needed
        if (dri_found)
        {
            SetWBE(p, restart_interval);
            p += 2;
            // restart_count. Hardcoded same value as in gstreamer implementation
            SetWBE(p, 0xffff);
            p += 2;
        }

        if (off == 0 && nb_qtables)
        {
            /* set quantization tables header */
            *p++ = 0;
            *p++ = 0;
            SetWBE (p, 64 * nb_qtables);
            p += 2;
            for (int i = 0; i < nb_qtables; i++)
            {
                memcpy (p, &qtables[65 * i + 1], 64);
                p += 64;
            }
        }

        /* rtp common header */
        rtp_packetize_common( id, out, (i_payload == i_data),
                      (in->i_pts > VLC_TS_INVALID ? in->i_pts : in->i_dts) );
        memcpy( p, p_data, i_payload );

        out->i_buffer = 12 + hdr_size + i_payload;
        out->i_dts    = in->i_dts;
        out->i_length = in->i_length;

        rtp_packetize_send( id, out );

        p_data += i_payload;
        i_data -= i_payload;
        off    += i_payload;
    }

    return VLC_SUCCESS;
}