libavcodec/libxvidff.c

   1 /*
   2  * Interface to xvidcore for mpeg4 encoding
   3  * Copyright (c) 2004 Adam Thayer <krevnik@comcast.net>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file xvidmpeg4.c
  24  * Interface to xvidcore for MPEG-4 compliant encoding.
  25  * @author Adam Thayer (krevnik@comcast.net)
  26  */
  27
  28 #include <xvid.h>
  29 #include <unistd.h>
  30 #include "avcodec.h"
  31 #include "libxvid_internal.h"
  32
  33 /**
  34  * Buffer management macros.
  35  */
  36 #define BUFFER_SIZE                 1024
  37 #define BUFFER_REMAINING(x)         (BUFFER_SIZE - strlen(x))
  38 #define BUFFER_CAT(x)               (&((x)[strlen(x)]))
  39
  40 /* For PPC Use */
  41 extern int has_altivec(void);
  42
  43 /**
  44  * Structure for the private Xvid context.
  45  * This stores all the private context for the codec.
  46  */
  47 typedef struct xvid_context {
  48     void *encoder_handle;          /** Handle for Xvid encoder */
  49     int xsize, ysize;              /** Frame size */
  50     int vop_flags;                 /** VOP flags for Xvid encoder */
  51     int vol_flags;                 /** VOL flags for Xvid encoder */
  52     int me_flags;                  /** Motion Estimation flags */
  53     int qscale;                    /** Do we use constant scale? */
  54     int quicktime_format;          /** Are we in a QT-based format? */
  55     AVFrame encoded_picture;       /** Encoded frame information */
  56     char *twopassbuffer;           /** Character buffer for two-pass */
  57     char *old_twopassbuffer;       /** Old character buffer (two-pass) */
  58     char *twopassfile;             /** second pass temp file name */
  59     unsigned char *intra_matrix;   /** P-Frame Quant Matrix */
  60     unsigned char *inter_matrix;   /** I-Frame Quant Matrix */
  61 } xvid_context_t;
  62
  63 /**
  64  * Structure for the private first-pass plugin.
  65  */
  66 typedef struct xvid_ff_pass1 {
  67     int     version;                /** Xvid version */
  68     xvid_context_t *context;        /** Pointer to private context */
  69 } xvid_ff_pass1_t;
  70
  71 /* Prototypes - See function implementation for details */
  72 int xvid_strip_vol_header(AVCodecContext *avctx, unsigned char *frame, unsigned int header_len, unsigned int frame_len);
  73 int xvid_ff_2pass(void *ref, int opt, void *p1, void *p2);
  74 void xvid_correct_framerate(AVCodecContext *avctx);
  75
  76 /**
  77  * Creates the private context for the encoder.
  78  * All buffers are allocated, settings are loaded from the user,
  79  * and the encoder context created.
  80  *
  81  * @param avctx AVCodecContext pointer to context
  82  * @return Returns 0 on success, -1 on failure
  83  */
  84 av_cold int ff_xvid_encode_init(AVCodecContext *avctx)  {
  85     int xerr, i;
  86     int xvid_flags = avctx->flags;
  87     xvid_context_t *x = avctx->priv_data;
  88     uint16_t *intra, *inter;
  89     int fd;
  90
  91     xvid_plugin_single_t single;
  92     xvid_ff_pass1_t rc2pass1;
  93     xvid_plugin_2pass2_t rc2pass2;
  94     xvid_gbl_init_t xvid_gbl_init;
  95     xvid_enc_create_t xvid_enc_create;
  96     xvid_enc_plugin_t plugins[7];
  97
  98     /* Bring in VOP flags from ffmpeg command-line */
  99     x->vop_flags = XVID_VOP_HALFPEL; /* Bare minimum quality */
 100     if( xvid_flags & CODEC_FLAG_4MV )
 101         x->vop_flags |= XVID_VOP_INTER4V; /* Level 3 */
 102     if( avctx->trellis
 103         )
 104         x->vop_flags |= XVID_VOP_TRELLISQUANT; /* Level 5 */
 105     if( xvid_flags & CODEC_FLAG_AC_PRED )
 106         x->vop_flags |= XVID_VOP_HQACPRED; /* Level 6 */
 107     if( xvid_flags & CODEC_FLAG_GRAY )
 108         x->vop_flags |= XVID_VOP_GREYSCALE;
 109
 110     /* Decide which ME quality setting to use */
 111     x->me_flags = 0;
 112     switch( avctx->me_method ) {
 113        case ME_FULL:   /* Quality 6 */
 114            x->me_flags |=  XVID_ME_EXTSEARCH16
 115                        |   XVID_ME_EXTSEARCH8;
 116
 117        case ME_EPZS:   /* Quality 4 */
 118            x->me_flags |=  XVID_ME_ADVANCEDDIAMOND8
 119                        |   XVID_ME_HALFPELREFINE8
 120                        |   XVID_ME_CHROMA_PVOP
 121                        |   XVID_ME_CHROMA_BVOP;
 122
 123        case ME_LOG:    /* Quality 2 */
 124        case ME_PHODS:
 125        case ME_X1:
 126            x->me_flags |=  XVID_ME_ADVANCEDDIAMOND16
 127                        |   XVID_ME_HALFPELREFINE16;
 128
 129        case ME_ZERO:   /* Quality 0 */
 130        default:
 131            break;
 132     }
 133
 134     /* Decide how we should decide blocks */
 135     switch( avctx->mb_decision ) {
 136        case 2:
 137            x->vop_flags |= XVID_VOP_MODEDECISION_RD;
 138            x->me_flags |=  XVID_ME_HALFPELREFINE8_RD
 139                        |   XVID_ME_QUARTERPELREFINE8_RD
 140                        |   XVID_ME_EXTSEARCH_RD
 141                        |   XVID_ME_CHECKPREDICTION_RD;
 142        case 1:
 143            if( !(x->vop_flags & XVID_VOP_MODEDECISION_RD) )
 144                x->vop_flags |= XVID_VOP_FAST_MODEDECISION_RD;
 145            x->me_flags |=  XVID_ME_HALFPELREFINE16_RD
 146                        |   XVID_ME_QUARTERPELREFINE16_RD;
 147
 148        default:
 149            break;
 150     }
 151
 152     /* Bring in VOL flags from ffmpeg command-line */
 153     x->vol_flags = 0;
 154     if( xvid_flags & CODEC_FLAG_GMC ) {
 155         x->vol_flags |= XVID_VOL_GMC;
 156         x->me_flags |= XVID_ME_GME_REFINE;
 157     }
 158     if( xvid_flags & CODEC_FLAG_QPEL ) {
 159         x->vol_flags |= XVID_VOL_QUARTERPEL;
 160         x->me_flags |= XVID_ME_QUARTERPELREFINE16;
 161         if( x->vop_flags & XVID_VOP_INTER4V )
 162             x->me_flags |= XVID_ME_QUARTERPELREFINE8;
 163     }
 164
 165     memset(&xvid_gbl_init, 0, sizeof(xvid_gbl_init));
 166     xvid_gbl_init.version = XVID_VERSION;
 167     xvid_gbl_init.debug = 0;
 168
 169 #ifdef ARCH_POWERPC
 170     /* Xvid's PPC support is borked, use libavcodec to detect */
 171 #ifdef HAVE_ALTIVEC
 172     if( has_altivec() ) {
 173         xvid_gbl_init.cpu_flags = XVID_CPU_FORCE | XVID_CPU_ALTIVEC;
 174     } else
 175 #endif
 176         xvid_gbl_init.cpu_flags = XVID_CPU_FORCE;
 177 #else
 178     /* Xvid can detect on x86 */
 179     xvid_gbl_init.cpu_flags = 0;
 180 #endif
 181
 182     /* Initialize */
 183     xvid_global(NULL, XVID_GBL_INIT, &xvid_gbl_init, NULL);
 184
 185     /* Create the encoder reference */
 186     memset(&xvid_enc_create, 0, sizeof(xvid_enc_create));
 187     xvid_enc_create.version = XVID_VERSION;
 188
 189     /* Store the desired frame size */
 190     xvid_enc_create.width = x->xsize = avctx->width;
 191     xvid_enc_create.height = x->ysize = avctx->height;
 192
 193     /* Xvid can determine the proper profile to use */
 194     /* xvid_enc_create.profile = XVID_PROFILE_S_L3; */
 195
 196     /* We don't use zones */
 197     xvid_enc_create.zones = NULL;
 198     xvid_enc_create.num_zones = 0;
 199
 200     xvid_enc_create.num_threads = avctx->thread_count;
 201
 202     xvid_enc_create.plugins = plugins;
 203     xvid_enc_create.num_plugins = 0;
 204
 205     /* Initialize Buffers */
 206     x->twopassbuffer = NULL;
 207     x->old_twopassbuffer = NULL;
 208     x->twopassfile = NULL;
 209
 210     if( xvid_flags & CODEC_FLAG_PASS1 ) {
 211         memset(&rc2pass1, 0, sizeof(xvid_ff_pass1_t));
 212         rc2pass1.version = XVID_VERSION;
 213         rc2pass1.context = x;
 214         x->twopassbuffer = av_malloc(BUFFER_SIZE);
 215         x->old_twopassbuffer = av_malloc(BUFFER_SIZE);
 216         if( x->twopassbuffer == NULL || x->old_twopassbuffer == NULL ) {
 217             av_log(avctx, AV_LOG_ERROR,
 218                 "Xvid: Cannot allocate 2-pass log buffers\n");
 219             return -1;
 220         }
 221         x->twopassbuffer[0] = x->old_twopassbuffer[0] = 0;
 222
 223         plugins[xvid_enc_create.num_plugins].func = xvid_ff_2pass;
 224         plugins[xvid_enc_create.num_plugins].param = &rc2pass1;
 225         xvid_enc_create.num_plugins++;
 226     } else if( xvid_flags & CODEC_FLAG_PASS2 ) {
 227         memset(&rc2pass2, 0, sizeof(xvid_plugin_2pass2_t));
 228         rc2pass2.version = XVID_VERSION;
 229         rc2pass2.bitrate = avctx->bit_rate;
 230
 231         fd = av_tempfile("xvidff.", &(x->twopassfile));
 232         if( fd == -1 ) {
 233             av_log(avctx, AV_LOG_ERROR,
 234                 "Xvid: Cannot write 2-pass pipe\n");
 235             return -1;
 236         }
 237
 238         if( avctx->stats_in == NULL ) {
 239             av_log(avctx, AV_LOG_ERROR,
 240                 "Xvid: No 2-pass information loaded for second pass\n");
 241             return -1;
 242         }
 243
 244         if( strlen(avctx->stats_in) >
 245               write(fd, avctx->stats_in, strlen(avctx->stats_in)) ) {
 246             close(fd);
 247             av_log(avctx, AV_LOG_ERROR,
 248                 "Xvid: Cannot write to 2-pass pipe\n");
 249             return -1;
 250         }
 251
 252         close(fd);
 253         rc2pass2.filename = x->twopassfile;
 254         plugins[xvid_enc_create.num_plugins].func = xvid_plugin_2pass2;
 255         plugins[xvid_enc_create.num_plugins].param = &rc2pass2;
 256         xvid_enc_create.num_plugins++;
 257     } else if( !(xvid_flags & CODEC_FLAG_QSCALE) ) {
 258         /* Single Pass Bitrate Control! */
 259         memset(&single, 0, sizeof(xvid_plugin_single_t));
 260         single.version = XVID_VERSION;
 261         single.bitrate = avctx->bit_rate;
 262
 263         plugins[xvid_enc_create.num_plugins].func = xvid_plugin_single;
 264         plugins[xvid_enc_create.num_plugins].param = &single;
 265         xvid_enc_create.num_plugins++;
 266     }
 267
 268     /* Luminance Masking */
 269     if( 0.0 != avctx->lumi_masking ) {
 270         plugins[xvid_enc_create.num_plugins].func = xvid_plugin_lumimasking;
 271         plugins[xvid_enc_create.num_plugins].param = NULL;
 272         xvid_enc_create.num_plugins++;
 273     }
 274
 275     /* Frame Rate and Key Frames */
 276     xvid_correct_framerate(avctx);
 277     xvid_enc_create.fincr = avctx->time_base.num;
 278     xvid_enc_create.fbase = avctx->time_base.den;
 279     if( avctx->gop_size > 0 )
 280         xvid_enc_create.max_key_interval = avctx->gop_size;
 281     else
 282         xvid_enc_create.max_key_interval = 240; /* Xvid's best default */
 283
 284     /* Quants */
 285     if( xvid_flags & CODEC_FLAG_QSCALE ) x->qscale = 1;
 286     else x->qscale = 0;
 287
 288     xvid_enc_create.min_quant[0] = avctx->qmin;
 289     xvid_enc_create.min_quant[1] = avctx->qmin;
 290     xvid_enc_create.min_quant[2] = avctx->qmin;
 291     xvid_enc_create.max_quant[0] = avctx->qmax;
 292     xvid_enc_create.max_quant[1] = avctx->qmax;
 293     xvid_enc_create.max_quant[2] = avctx->qmax;
 294
 295     /* Quant Matrices */
 296     x->intra_matrix = x->inter_matrix = NULL;
 297     if( avctx->mpeg_quant )
 298        x->vol_flags |= XVID_VOL_MPEGQUANT;
 299     if( (avctx->intra_matrix || avctx->inter_matrix) ) {
 300        x->vol_flags |= XVID_VOL_MPEGQUANT;
 301
 302        if( avctx->intra_matrix ) {
 303            intra = avctx->intra_matrix;
 304            x->intra_matrix = av_malloc(sizeof(unsigned char) * 64);
 305        } else
 306            intra = NULL;
 307        if( avctx->inter_matrix ) {
 308            inter = avctx->inter_matrix;
 309            x->inter_matrix = av_malloc(sizeof(unsigned char) * 64);
 310        } else
 311            inter = NULL;
 312
 313        for( i = 0; i < 64; i++ ) {
 314            if( intra )
 315                x->intra_matrix[i] = (unsigned char)intra[i];
 316            if( inter )
 317                x->inter_matrix[i] = (unsigned char)inter[i];
 318        }
 319     }
 320
 321     /* Misc Settings */
 322     xvid_enc_create.frame_drop_ratio = 0;
 323     xvid_enc_create.global = 0;
 324     if( xvid_flags & CODEC_FLAG_CLOSED_GOP )
 325         xvid_enc_create.global |= XVID_GLOBAL_CLOSED_GOP;
 326
 327     /* Determines which codec mode we are operating in */
 328     avctx->extradata = NULL;
 329     avctx->extradata_size = 0;
 330     if( xvid_flags & CODEC_FLAG_GLOBAL_HEADER ) {
 331         /* In this case, we are claiming to be MPEG4 */
 332         x->quicktime_format = 1;
 333         avctx->codec_id = CODEC_ID_MPEG4;
 334     } else {
 335         /* We are claiming to be Xvid */
 336         x->quicktime_format = 0;
 337         if(!avctx->codec_tag)
 338             avctx->codec_tag = ff_get_fourcc("xvid");
 339     }
 340
 341     /* Bframes */
 342     xvid_enc_create.max_bframes = avctx->max_b_frames;
 343     xvid_enc_create.bquant_offset = 100 * avctx->b_quant_offset;
 344     xvid_enc_create.bquant_ratio = 100 * avctx->b_quant_factor;
 345     if( avctx->max_b_frames > 0  && !x->quicktime_format ) xvid_enc_create.global |= XVID_GLOBAL_PACKED;
 346
 347     /* Create encoder context */
 348     xerr = xvid_encore(NULL, XVID_ENC_CREATE, &xvid_enc_create, NULL);
 349     if( xerr ) {
 350         av_log(avctx, AV_LOG_ERROR, "Xvid: Could not create encoder reference\n");
 351         return -1;
 352     }
 353
 354     x->encoder_handle = xvid_enc_create.handle;
 355     avctx->coded_frame = &x->encoded_picture;
 356
 357     return 0;
 358 }
 359
 360 /**
 361  * Encodes a single frame.
 362  *
 363  * @param avctx AVCodecContext pointer to context
 364  * @param frame Pointer to encoded frame buffer
 365  * @param buf_size Size of encoded frame buffer
 366  * @param data Pointer to AVFrame of unencoded frame
 367  * @return Returns 0 on success, -1 on failure
 368  */
 369 int ff_xvid_encode_frame(AVCodecContext *avctx,
 370                          unsigned char *frame, int buf_size, void *data) {
 371     int xerr, i;
 372     char *tmp;
 373     xvid_context_t *x = avctx->priv_data;
 374     AVFrame *picture = data;
 375     AVFrame *p = &(x->encoded_picture);
 376
 377     xvid_enc_frame_t xvid_enc_frame;
 378     xvid_enc_stats_t xvid_enc_stats;
 379
 380     /* Start setting up the frame */
 381     memset(&xvid_enc_frame, 0, sizeof(xvid_enc_frame));
 382     xvid_enc_frame.version = XVID_VERSION;
 383     memset(&xvid_enc_stats, 0, sizeof(xvid_enc_stats));
 384     xvid_enc_stats.version = XVID_VERSION;
 385     *p = *picture;
 386
 387     /* Let Xvid know where to put the frame. */
 388     xvid_enc_frame.bitstream = frame;
 389     xvid_enc_frame.length = buf_size;
 390
 391     /* Initialize input image fields */
 392     if( avctx->pix_fmt != PIX_FMT_YUV420P ) {
 393         av_log(avctx, AV_LOG_ERROR, "Xvid: Color spaces other than 420p not supported\n");
 394         return -1;
 395     }
 396
 397     xvid_enc_frame.input.csp = XVID_CSP_PLANAR; /* YUV420P */
 398
 399     for( i = 0; i < 4; i++ ) {
 400         xvid_enc_frame.input.plane[i] = picture->data[i];
 401         xvid_enc_frame.input.stride[i] = picture->linesize[i];
 402     }
 403
 404     /* Encoder Flags */
 405     xvid_enc_frame.vop_flags = x->vop_flags;
 406     xvid_enc_frame.vol_flags = x->vol_flags;
 407     xvid_enc_frame.motion = x->me_flags;
 408     xvid_enc_frame.type = XVID_TYPE_AUTO;
 409
 410     /* Pixel aspect ratio setting */
 411     if (avctx->sample_aspect_ratio.num < 1 || avctx->sample_aspect_ratio.num > 255 ||
 412         avctx->sample_aspect_ratio.den < 1 || avctx->sample_aspect_ratio.den > 255) {
 413         av_log(avctx, AV_LOG_ERROR, "Invalid pixel aspect ratio %i/%i\n",
 414                avctx->sample_aspect_ratio.num, avctx->sample_aspect_ratio.den);
 415         return -1;
 416     }
 417     xvid_enc_frame.par = XVID_PAR_EXT;
 418     xvid_enc_frame.par_width  = avctx->sample_aspect_ratio.num;
 419     xvid_enc_frame.par_height = avctx->sample_aspect_ratio.den;
 420
 421     /* Quant Setting */
 422     if( x->qscale ) xvid_enc_frame.quant = picture->quality / FF_QP2LAMBDA;
 423     else xvid_enc_frame.quant = 0;
 424
 425     /* Matrices */
 426     xvid_enc_frame.quant_intra_matrix = x->intra_matrix;
 427     xvid_enc_frame.quant_inter_matrix = x->inter_matrix;
 428
 429     /* Encode */
 430     xerr = xvid_encore(x->encoder_handle, XVID_ENC_ENCODE,
 431         &xvid_enc_frame, &xvid_enc_stats);
 432
 433     /* Two-pass log buffer swapping */
 434     avctx->stats_out = NULL;
 435     if( x->twopassbuffer ) {
 436         tmp = x->old_twopassbuffer;
 437         x->old_twopassbuffer = x->twopassbuffer;
 438         x->twopassbuffer = tmp;
 439         x->twopassbuffer[0] = 0;
 440         if( x->old_twopassbuffer[0] != 0 ) {
 441             avctx->stats_out = x->old_twopassbuffer;
 442         }
 443     }
 444
 445     if( 0 <= xerr ) {
 446         p->quality = xvid_enc_stats.quant * FF_QP2LAMBDA;
 447         if( xvid_enc_stats.type == XVID_TYPE_PVOP )
 448             p->pict_type = FF_P_TYPE;
 449         else if( xvid_enc_stats.type == XVID_TYPE_BVOP )
 450             p->pict_type = FF_B_TYPE;
 451         else if( xvid_enc_stats.type == XVID_TYPE_SVOP )
 452             p->pict_type = FF_S_TYPE;
 453         else
 454             p->pict_type = FF_I_TYPE;
 455         if( xvid_enc_frame.out_flags & XVID_KEYFRAME ) {
 456             p->key_frame = 1;
 457             if( x->quicktime_format )
 458                 return xvid_strip_vol_header(avctx, frame,
 459                     xvid_enc_stats.hlength, xerr);
 460          } else
 461             p->key_frame = 0;
 462
 463         return xerr;
 464     } else {
 465         av_log(avctx, AV_LOG_ERROR, "Xvid: Encoding Error Occurred: %i\n", xerr);
 466         return -1;
 467     }
 468 }
 469
 470 /**
 471  * Destroys the private context for the encoder.
 472  * All buffers are freed, and the Xvid encoder context is destroyed.
 473  *
 474  * @param avctx AVCodecContext pointer to context
 475  * @return Returns 0, success guaranteed
 476  */
 477 av_cold int ff_xvid_encode_close(AVCodecContext *avctx) {
 478     xvid_context_t *x = avctx->priv_data;
 479
 480     xvid_encore(x->encoder_handle, XVID_ENC_DESTROY, NULL, NULL);
 481
 482     if( avctx->extradata != NULL )
 483         av_free(avctx->extradata);
 484     if( x->twopassbuffer != NULL ) {
 485         av_free(x->twopassbuffer);
 486         av_free(x->old_twopassbuffer);
 487     }
 488     if( x->twopassfile != NULL )
 489         av_free(x->twopassfile);
 490     if( x->intra_matrix != NULL )
 491         av_free(x->intra_matrix);
 492     if( x->inter_matrix != NULL )
 493         av_free(x->inter_matrix);
 494
 495     return 0;
 496 }
 497
 498 /**
 499  * Routine to create a global VO/VOL header for MP4 container.
 500  * What we do here is extract the header from the Xvid bitstream
 501  * as it is encoded. We also strip the repeated headers from the
 502  * bitstream when a global header is requested for MPEG-4 ISO
 503  * compliance.
 504  *
 505  * @param avctx AVCodecContext pointer to context
 506  * @param frame Pointer to encoded frame data
 507  * @param header_len Length of header to search
 508  * @param frame_len Length of encoded frame data
 509  * @return Returns new length of frame data
 510  */
 511 int xvid_strip_vol_header(AVCodecContext *avctx,
 512                   unsigned char *frame,
 513                   unsigned int header_len,
 514                   unsigned int frame_len) {
 515     int vo_len = 0, i;
 516
 517     for( i = 0; i < header_len - 3; i++ ) {
 518         if( frame[i] == 0x00 &&
 519             frame[i+1] == 0x00 &&
 520             frame[i+2] == 0x01 &&
 521             frame[i+3] == 0xB6 ) {
 522             vo_len = i;
 523             break;
 524         }
 525     }
 526
 527     if( vo_len > 0 ) {
 528         /* We need to store the header, so extract it */
 529         if( avctx->extradata == NULL ) {
 530             avctx->extradata = av_malloc(vo_len);
 531             memcpy(avctx->extradata, frame, vo_len);
 532             avctx->extradata_size = vo_len;
 533         }
 534         /* Less dangerous now, memmove properly copies the two
 535            chunks of overlapping data */
 536         memmove(frame, &(frame[vo_len]), frame_len - vo_len);
 537         return frame_len - vo_len;
 538     } else
 539         return frame_len;
 540 }
 541
 542 /**
 543  * Routine to correct a possibly erroneous framerate being fed to us.
 544  * Xvid currently chokes on framerates where the ticks per frame is
 545  * extremely large. This function works to correct problems in this area
 546  * by estimating a new framerate and taking the simpler fraction of
 547  * the two presented.
 548  *
 549  * @param avctx Context that contains the framerate to correct.
 550  */
 551 void xvid_correct_framerate(AVCodecContext *avctx) {
 552     int frate, fbase;
 553     int est_frate, est_fbase;
 554     int gcd;
 555     float est_fps, fps;
 556
 557     frate = avctx->time_base.den;
 558     fbase = avctx->time_base.num;
 559
 560     gcd = ff_gcd(frate, fbase);
 561     if( gcd > 1 ) {
 562         frate /= gcd;
 563         fbase /= gcd;
 564     }
 565
 566     if( frate <= 65000 && fbase <= 65000 ) {
 567         avctx->time_base.den = frate;
 568         avctx->time_base.num = fbase;
 569         return;
 570     }
 571
 572     fps = (float)frate / (float)fbase;
 573     est_fps = roundf(fps * 1000.0) / 1000.0;
 574
 575     est_frate = (int)est_fps;
 576     if( est_fps > (int)est_fps ) {
 577         est_frate = (est_frate + 1) * 1000;
 578         est_fbase = (int)roundf((float)est_frate / est_fps);
 579     } else
 580         est_fbase = 1;
 581
 582     gcd = ff_gcd(est_frate, est_fbase);
 583     if( gcd > 1 ) {
 584         est_frate /= gcd;
 585         est_fbase /= gcd;
 586     }
 587
 588     if( fbase > est_fbase ) {
 589         avctx->time_base.den = est_frate;
 590         avctx->time_base.num = est_fbase;
 591         av_log(avctx, AV_LOG_DEBUG,
 592             "Xvid: framerate re-estimated: %.2f, %.3f%% correction\n",
 593             est_fps, (((est_fps - fps)/fps) * 100.0));
 594     } else {
 595         avctx->time_base.den = frate;
 596         avctx->time_base.num = fbase;
 597     }
 598 }
 599
 600 /*
 601  * Xvid 2-Pass Kludge Section
 602  *
 603  * Xvid's default 2-pass doesn't allow us to create data as we need to, so
 604  * this section spends time replacing the first pass plugin so we can write
 605  * statistic information as libavcodec requests in. We have another kludge
 606  * that allows us to pass data to the second pass in Xvid without a custom
 607  * rate-control plugin.
 608  */
 609
 610 /**
 611  * Initializes the two-pass plugin and context.
 612  *
 613  * @param param Input construction parameter structure
 614  * @param handle Private context handle
 615  * @return Returns XVID_ERR_xxxx on failure, or 0 on success.
 616  */
 617 static int xvid_ff_2pass_create(xvid_plg_create_t * param,
 618                                 void ** handle) {
 619     xvid_ff_pass1_t *x = (xvid_ff_pass1_t *)param->param;
 620     char *log = x->context->twopassbuffer;
 621
 622     /* Do a quick bounds check */
 623     if( log == NULL )
 624         return XVID_ERR_FAIL;
 625
 626     /* We use snprintf() */
 627     /* This is because we can safely prevent a buffer overflow */
 628     log[0] = 0;
 629     snprintf(log, BUFFER_REMAINING(log),
 630         "# ffmpeg 2-pass log file, using xvid codec\n");
 631     snprintf(BUFFER_CAT(log), BUFFER_REMAINING(log),
 632         "# Do not modify. libxvidcore version: %d.%d.%d\n\n",
 633         XVID_VERSION_MAJOR(XVID_VERSION),
 634         XVID_VERSION_MINOR(XVID_VERSION),
 635         XVID_VERSION_PATCH(XVID_VERSION));
 636
 637     *handle = x->context;
 638     return 0;
 639 }
 640
 641 /**
 642  * Destroys the two-pass plugin context.
 643  *
 644  * @param ref Context pointer for the plugin
 645  * @param param Destrooy context
 646  * @return Returns 0, success guaranteed
 647  */
 648 static int xvid_ff_2pass_destroy(xvid_context_t *ref,
 649                                 xvid_plg_destroy_t *param) {
 650     /* Currently cannot think of anything to do on destruction */
 651     /* Still, the framework should be here for reference/use */
 652     if( ref->twopassbuffer != NULL )
 653         ref->twopassbuffer[0] = 0;
 654     return 0;
 655 }
 656
 657 /**
 658  * Enables fast encode mode during the first pass.
 659  *
 660  * @param ref Context pointer for the plugin
 661  * @param param Frame data
 662  * @return Returns 0, success guaranteed
 663  */
 664 static int xvid_ff_2pass_before(xvid_context_t *ref,
 665                                 xvid_plg_data_t *param) {
 666     int motion_remove;
 667     int motion_replacements;
 668     int vop_remove;
 669
 670     /* Nothing to do here, result is changed too much */
 671     if( param->zone && param->zone->mode == XVID_ZONE_QUANT )
 672         return 0;
 673
 674     /* We can implement a 'turbo' first pass mode here */
 675     param->quant = 2;
 676
 677     /* Init values */
 678     motion_remove = ~XVID_ME_CHROMA_PVOP &
 679                     ~XVID_ME_CHROMA_BVOP &
 680                     ~XVID_ME_EXTSEARCH16 &
 681                     ~XVID_ME_ADVANCEDDIAMOND16;
 682     motion_replacements = XVID_ME_FAST_MODEINTERPOLATE |
 683                           XVID_ME_SKIP_DELTASEARCH |
 684                           XVID_ME_FASTREFINE16 |
 685                           XVID_ME_BFRAME_EARLYSTOP;
 686     vop_remove = ~XVID_VOP_MODEDECISION_RD &
 687                  ~XVID_VOP_FAST_MODEDECISION_RD &
 688                  ~XVID_VOP_TRELLISQUANT &
 689                  ~XVID_VOP_INTER4V &
 690                  ~XVID_VOP_HQACPRED;
 691
 692     param->vol_flags &= ~XVID_VOL_GMC;
 693     param->vop_flags &= vop_remove;
 694     param->motion_flags &= motion_remove;
 695     param->motion_flags |= motion_replacements;
 696
 697     return 0;
 698 }
 699
 700 /**
 701  * Captures statistic data and writes it during first pass.
 702  *
 703  * @param ref Context pointer for the plugin
 704  * @param param Statistic data
 705  * @return Returns XVID_ERR_xxxx on failure, or 0 on success
 706  */
 707 static int xvid_ff_2pass_after(xvid_context_t *ref,
 708                                 xvid_plg_data_t *param) {
 709     char *log = ref->twopassbuffer;
 710     char *frame_types = " ipbs";
 711     char frame_type;
 712
 713     /* Quick bounds check */
 714     if( log == NULL )
 715         return XVID_ERR_FAIL;
 716
 717     /* Convert the type given to us into a character */
 718     if( param->type < 5 && param->type > 0 ) {
 719         frame_type = frame_types[param->type];
 720     } else {
 721         return XVID_ERR_FAIL;
 722     }
 723
 724     snprintf(BUFFER_CAT(log), BUFFER_REMAINING(log),
 725         "%c %d %d %d %d %d %d\n",
 726         frame_type, param->stats.quant, param->stats.kblks, param->stats.mblks,
 727         param->stats.ublks, param->stats.length, param->stats.hlength);
 728
 729     return 0;
 730 }
 731
 732 /**
 733  * Dispatch function for our custom plugin.
 734  * This handles the dispatch for the Xvid plugin. It passes data
 735  * on to other functions for actual processing.
 736  *
 737  * @param ref Context pointer for the plugin
 738  * @param cmd The task given for us to complete
 739  * @param p1 First parameter (varies)
 740  * @param p2 Second parameter (varies)
 741  * @return Returns XVID_ERR_xxxx on failure, or 0 on success
 742  */
 743 int xvid_ff_2pass(void *ref, int cmd, void *p1, void *p2) {
 744     switch( cmd ) {
 745         case XVID_PLG_INFO:
 746         case XVID_PLG_FRAME:
 747             return 0;
 748
 749         case XVID_PLG_BEFORE:
 750             return xvid_ff_2pass_before(ref, p1);
 751
 752         case XVID_PLG_CREATE:
 753             return xvid_ff_2pass_create(p1, p2);
 754
 755         case XVID_PLG_AFTER:
 756             return xvid_ff_2pass_after(ref, p1);
 757
 758         case XVID_PLG_DESTROY:
 759             return xvid_ff_2pass_destroy(ref, p1);
 760
 761         default:
 762             return XVID_ERR_FAIL;
 763     }
 764 }
 765
 766 /**
 767  * Xvid codec definition for libavcodec.
 768  */
 769 AVCodec libxvid_encoder = {
 770     "libxvid",
 771     CODEC_TYPE_VIDEO,
 772     CODEC_ID_XVID,
 773     sizeof(xvid_context_t),
 774     ff_xvid_encode_init,
 775     ff_xvid_encode_frame,
 776     ff_xvid_encode_close,
 777     .pix_fmts= (enum PixelFormat[]){PIX_FMT_YUV420P, PIX_FMT_NONE},
 778     .long_name= NULL_IF_CONFIG_SMALL("libxvidcore MPEG-4 part 2"),
 779 };