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