webmdec.c

   1 /*
   2  *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11 #include "./webmdec.h"
  12
  13 #include <stdarg.h>
  14
  15 #include "third_party/nestegg/include/nestegg/nestegg.h"
  16
  17 static int nestegg_read_cb(void *buffer, size_t length, void *userdata) {
  18   FILE *f = userdata;
  19
  20   if (fread(buffer, 1, length, f) < length) {
  21     if (ferror(f))
  22       return -1;
  23     if (feof(f))
  24       return 0;
  25   }
  26   return 1;
  27 }
  28
  29 static int nestegg_seek_cb(int64_t offset, int whence, void *userdata) {
  30   switch (whence) {
  31     case NESTEGG_SEEK_SET:
  32       whence = SEEK_SET;
  33       break;
  34     case NESTEGG_SEEK_CUR:
  35       whence = SEEK_CUR;
  36       break;
  37     case NESTEGG_SEEK_END:
  38       whence = SEEK_END;
  39       break;
  40   };
  41   return fseek(userdata, (int32_t)offset, whence) ? -1 : 0;
  42 }
  43
  44 static int64_t nestegg_tell_cb(void *userdata) {
  45   return ftell(userdata);
  46 }
  47
  48 static void nestegg_log_cb(nestegg *context,
  49                            unsigned int severity,
  50                            char const *format, ...) {
  51   va_list ap;
  52   va_start(ap, format);
  53   vfprintf(stderr, format, ap);
  54   fprintf(stderr, "\n");
  55   va_end(ap);
  56 }
  57
  58 int file_is_webm(struct WebmInputContext *webm_ctx,
  59                  struct VpxInputContext *vpx_ctx) {
  60   uint32_t i, n;
  61   int track_type = -1;
  62   int codec_id;
  63
  64   nestegg_io io = {nestegg_read_cb, nestegg_seek_cb, nestegg_tell_cb, 0};
  65   nestegg_video_params params;
  66
  67   io.userdata = vpx_ctx->file;
  68   if (nestegg_init(&webm_ctx->nestegg_ctx, io, NULL, -1))
  69     goto fail;
  70
  71   if (nestegg_track_count(webm_ctx->nestegg_ctx, &n))
  72     goto fail;
  73
  74   for (i = 0; i < n; i++) {
  75     track_type = nestegg_track_type(webm_ctx->nestegg_ctx, i);
  76
  77     if (track_type == NESTEGG_TRACK_VIDEO)
  78       break;
  79     else if (track_type < 0)
  80       goto fail;
  81   }
  82
  83   codec_id = nestegg_track_codec_id(webm_ctx->nestegg_ctx, i);
  84   if (codec_id == NESTEGG_CODEC_VP8) {
  85     vpx_ctx->fourcc = VP8_FOURCC;
  86   } else if (codec_id == NESTEGG_CODEC_VP9) {
  87     vpx_ctx->fourcc = VP9_FOURCC;
  88   } else {
  89     fatal("Not VPx video, quitting.\n");
  90   }
  91
  92   webm_ctx->video_track = i;
  93
  94   if (nestegg_track_video_params(webm_ctx->nestegg_ctx, i, &params))
  95     goto fail;
  96
  97   vpx_ctx->framerate.denominator = 0;
  98   vpx_ctx->framerate.numerator = 0;
  99   vpx_ctx->width = params.width;
 100   vpx_ctx->height = params.height;
 101
 102   return 1;
 103
 104  fail:
 105   webm_ctx->nestegg_ctx = NULL;
 106   rewind(vpx_ctx->file);
 107
 108   return 0;
 109 }
 110
 111 int webm_read_frame(struct WebmInputContext *webm_ctx,
 112                     uint8_t **buffer,
 113                     size_t *bytes_in_buffer,
 114                     size_t *buffer_size) {
 115   if (webm_ctx->chunk >= webm_ctx->chunks) {
 116     uint32_t track;
 117
 118     do {
 119       /* End of this packet, get another. */
 120       if (webm_ctx->pkt) {
 121         nestegg_free_packet(webm_ctx->pkt);
 122         webm_ctx->pkt = NULL;
 123       }
 124
 125       if (nestegg_read_packet(webm_ctx->nestegg_ctx, &webm_ctx->pkt) <= 0 ||
 126           nestegg_packet_track(webm_ctx->pkt, &track)) {
 127         return 1;
 128       }
 129     } while (track != webm_ctx->video_track);
 130
 131     if (nestegg_packet_count(webm_ctx->pkt, &webm_ctx->chunks))
 132       return 1;
 133
 134     webm_ctx->chunk = 0;
 135   }
 136
 137   if (nestegg_packet_data(webm_ctx->pkt, webm_ctx->chunk,
 138                           buffer, bytes_in_buffer)) {
 139     return 1;
 140   }
 141
 142   webm_ctx->chunk++;
 143   return 0;
 144 }
 145
 146 int webm_guess_framerate(struct WebmInputContext *webm_ctx,
 147                          struct VpxInputContext *vpx_ctx) {
 148   uint32_t i;
 149   uint64_t tstamp = 0;
 150
 151   /* Check to see if we can seek before we parse any data. */
 152   if (nestegg_track_seek(webm_ctx->nestegg_ctx, webm_ctx->video_track, 0)) {
 153     warn("Failed to guess framerate (no Cues), set to 30fps.\n");
 154     vpx_ctx->framerate.numerator = 30;
 155     vpx_ctx->framerate.denominator  = 1;
 156     return 0;
 157   }
 158
 159   /* Guess the framerate. Read up to 1 second, or 50 video packets,
 160    * whichever comes first.
 161    */
 162   for (i = 0; tstamp < 1000000000 && i < 50;) {
 163     nestegg_packet *pkt;
 164     uint32_t track;
 165
 166     if (nestegg_read_packet(webm_ctx->nestegg_ctx, &pkt) <= 0)
 167       break;
 168
 169     nestegg_packet_track(pkt, &track);
 170     if (track == webm_ctx->video_track) {
 171       nestegg_packet_tstamp(pkt, &tstamp);
 172       ++i;
 173     }
 174
 175     nestegg_free_packet(pkt);
 176   }
 177
 178   if (nestegg_track_seek(webm_ctx->nestegg_ctx, webm_ctx->video_track, 0))
 179     goto fail;
 180
 181   vpx_ctx->framerate.numerator = (i - 1) * 1000000;
 182   vpx_ctx->framerate.denominator = (int)(tstamp / 1000);
 183   return 0;
 184
 185  fail:
 186   nestegg_destroy(webm_ctx->nestegg_ctx);
 187   webm_ctx->nestegg_ctx = NULL;
 188   rewind(vpx_ctx->file);
 189   return 1;
 190 }
 191
 192 void webm_free(struct WebmInputContext *webm_ctx) {
 193   if (webm_ctx && webm_ctx->nestegg_ctx) {
 194     if (webm_ctx->pkt)
 195       nestegg_free_packet(webm_ctx->pkt);
 196     nestegg_destroy(webm_ctx->nestegg_ctx);
 197   }
 198 }