ffmpeg.c

ffmpeg源码分析

                            break;
                        case CODEC_TYPE_VIDEO:
                            ret = avcodec_encode_video(enc, bit_buffer, bit_buffer_size, NULL);
                            video_size += ret;
                            if(enc->coded_frame && enc->coded_frame->key_frame)
                                pkt.flags |= PKT_FLAG_KEY;
                            if (ost->logfile && enc->stats_out) {
                                fprintf(ost->logfile, "%s", enc->stats_out);
                            }
                            break;
                        default:
                            ret=-1;
                        }

                        if(ret<=0)
                            break;
                        pkt.data= bit_buffer;
                        pkt.size= ret;
                        if(enc->coded_frame && enc->coded_frame->pts != AV_NOPTS_VALUE)
                            pkt.pts= av_rescale_q(enc->coded_frame->pts, enc->time_base, ost->st->time_base);
                        av_interleaved_write_frame(os, &pkt);
                    }
                }
            }
        }
    }

    return 0;
 fail_decode:
    return -1;
}


/*
 * The following code is the main loop of the file converter
 */
static int av_encode(AVFormatContext **output_files,
                     int nb_output_files,
                     AVFormatContext **input_files,
                     int nb_input_files,
                     AVStreamMap *stream_maps, int nb_stream_maps)
{
    int ret, i, j, k, n, nb_istreams = 0, nb_ostreams = 0;
    AVFormatContext *is, *os;
    AVCodecContext *codec, *icodec;
    AVOutputStream *ost, **ost_table = NULL;
    AVInputStream *ist, **ist_table = NULL;
    AVInputFile *file_table;
    AVFormatContext *stream_no_data;
    int key;

    file_table= (AVInputFile*) av_mallocz(nb_input_files * sizeof(AVInputFile));
    if (!file_table)
        goto fail;

    /* input stream init */
    j = 0;
    for(i=0;i<nb_input_files;i++) {
        is = input_files[i];
        file_table[i].ist_index = j;
        file_table[i].nb_streams = is->nb_streams;
        j += is->nb_streams;
    }
    nb_istreams = j;

    ist_table = av_mallocz(nb_istreams * sizeof(AVInputStream *));
    if (!ist_table)
        goto fail;

    for(i=0;i<nb_istreams;i++) {
        ist = av_mallocz(sizeof(AVInputStream));
        if (!ist)
            goto fail;
        ist_table[i] = ist;
    }
    j = 0;
    for(i=0;i<nb_input_files;i++) {
        is = input_files[i];
        for(k=0;k<is->nb_streams;k++) {
            ist = ist_table[j++];
            ist->st = is->streams[k];
            ist->file_index = i;
            ist->index = k;
            ist->discard = 1; /* the stream is discarded by default
                                 (changed later) */

            if (ist->st->codec->rate_emu) {
                ist->start = av_gettime();
                ist->frame = 0;
            }
        }
    }

    /* output stream init */
    nb_ostreams = 0;
    for(i=0;i<nb_output_files;i++) {
        os = output_files[i];
        nb_ostreams += os->nb_streams;
    }
    if (nb_stream_maps > 0 && nb_stream_maps != nb_ostreams) {
        fprintf(stderr, "Number of stream maps must match number of output streams\n");
        exit(1);
    }

    /* Sanity check the mapping args -- do the input files & streams exist? */
    for(i=0;i<nb_stream_maps;i++) {
        int fi = stream_maps[i].file_index;
        int si = stream_maps[i].stream_index;

        if (fi < 0 || fi > nb_input_files - 1 ||
            si < 0 || si > file_table[fi].nb_streams - 1) {
            fprintf(stderr,"Could not find input stream #%d.%d\n", fi, si);
            exit(1);
        }
        fi = stream_maps[i].sync_file_index;
        si = stream_maps[i].sync_stream_index;
        if (fi < 0 || fi > nb_input_files - 1 ||
            si < 0 || si > file_table[fi].nb_streams - 1) {
            fprintf(stderr,"Could not find sync stream #%d.%d\n", fi, si);
            exit(1);
        }
    }

    ost_table = av_mallocz(sizeof(AVOutputStream *) * nb_ostreams);
    if (!ost_table)
        goto fail;
    for(i=0;i<nb_ostreams;i++) {
        ost = av_mallocz(sizeof(AVOutputStream));
        if (!ost)
            goto fail;
        ost_table[i] = ost;
    }

    n = 0;
    for(k=0;k<nb_output_files;k++) {
        os = output_files[k];
        for(i=0;i<os->nb_streams;i++) {
            int found;
            ost = ost_table[n++];
            ost->file_index = k;
            ost->index = i;
            ost->st = os->streams[i];
            if (nb_stream_maps > 0) {
                ost->source_index = file_table[stream_maps[n-1].file_index].ist_index +
                    stream_maps[n-1].stream_index;

                /* Sanity check that the stream types match */
                if (ist_table[ost->source_index]->st->codec->codec_type != ost->st->codec->codec_type) {
                    fprintf(stderr, "Codec type mismatch for mapping #%d.%d -> #%d.%d\n",
                        stream_maps[n-1].file_index, stream_maps[n-1].stream_index,
                        ost->file_index, ost->index);
                    exit(1);
                }

            } else {
                /* get corresponding input stream index : we select the first one with the right type */
                found = 0;
                for(j=0;j<nb_istreams;j++) {
                    ist = ist_table[j];
                    if (ist->discard &&
                        ist->st->codec->codec_type == ost->st->codec->codec_type) {
                        ost->source_index = j;
                        found = 1;
                        break;
                    }
                }

                if (!found) {
                    /* try again and reuse existing stream */
                    for(j=0;j<nb_istreams;j++) {
                        ist = ist_table[j];
                        if (ist->st->codec->codec_type == ost->st->codec->codec_type) {
                            ost->source_index = j;
                            found = 1;
                        }
                    }
                    if (!found) {
                        fprintf(stderr, "Could not find input stream matching output stream #%d.%d\n",
                                ost->file_index, ost->index);
                        exit(1);
                    }
                }
            }
            ist = ist_table[ost->source_index];
            ist->discard = 0;
            ost->sync_ist = (nb_stream_maps > 0) ?
                ist_table[file_table[stream_maps[n-1].sync_file_index].ist_index +
                         stream_maps[n-1].sync_stream_index] : ist;
        }
    }

    /* for each output stream, we compute the right encoding parameters */
    for(i=0;i<nb_ostreams;i++) {
        ost = ost_table[i];
        ist = ist_table[ost->source_index];

        codec = ost->st->codec;
        icodec = ist->st->codec;

        if (ost->st->stream_copy) {
            /* if stream_copy is selected, no need to decode or encode */
            codec->codec_id = icodec->codec_id;
            codec->codec_type = icodec->codec_type;
            if(!codec->codec_tag) codec->codec_tag = icodec->codec_tag;
            codec->bit_rate = icodec->bit_rate;
            codec->extradata= icodec->extradata;
            codec->extradata_size= icodec->extradata_size;
            codec->time_base = icodec->time_base;
            switch(codec->codec_type) {
            case CODEC_TYPE_AUDIO:
                codec->sample_rate = icodec->sample_rate;
                codec->channels = icodec->channels;
                codec->frame_size = icodec->frame_size;
                codec->block_align= icodec->block_align;
                break;
            case CODEC_TYPE_VIDEO:
                codec->pix_fmt = icodec->pix_fmt;
                codec->width = icodec->width;
                codec->height = icodec->height;
                codec->has_b_frames = icodec->has_b_frames;
                break;
            case CODEC_TYPE_SUBTITLE:
                break;
            default:
                av_abort();
            }
        } else {
            switch(codec->codec_type) {
            case CODEC_TYPE_AUDIO:
                if (fifo_init(&ost->fifo, 2 * MAX_AUDIO_PACKET_SIZE))
                    goto fail;

                if (codec->channels == icodec->channels &&
                    codec->sample_rate == icodec->sample_rate) {
                    ost->audio_resample = 0;
                } else {
                    if (codec->channels != icodec->channels &&
                        (icodec->codec_id == CODEC_ID_AC3 ||
                         icodec->codec_id == CODEC_ID_DTS)) {
                        /* Special case for 5:1 AC3 and DTS input */
                        /* and mono or stereo output      */
                        /* Request specific number of channels */
                        icodec->channels = codec->channels;
                        if (codec->sample_rate == icodec->sample_rate)
                            ost->audio_resample = 0;
                        else {
                            ost->audio_resample = 1;
                        }
                    } else {
                        ost->audio_resample = 1;
                    }
                }
                if(audio_sync_method>1)
                    ost->audio_resample = 1;

                if(ost->audio_resample){
                    ost->resample = audio_resample_init(codec->channels, icodec->channels,
                                                    codec->sample_rate, icodec->sample_rate);
                    if(!ost->resample){
                        printf("Can't resample.  Aborting.\n");
                        av_abort();
                    }
                }
                ist->decoding_needed = 1;
                ost->encoding_needed = 1;
                break;
            case CODEC_TYPE_VIDEO:
                if (codec->width == icodec->width &&
                    codec->height == icodec->height &&
                    frame_topBand == 0 &&
                    frame_bottomBand == 0 &&
                    frame_leftBand == 0 &&
                    frame_rightBand == 0 &&
                    frame_padtop == 0 &&
                    frame_padbottom == 0 &&
                    frame_padleft == 0 &&
                    frame_padright == 0)
                {
                    ost->video_resample = 0;
                    ost->video_crop = 0;
                    ost->video_pad = 0;
                } else if ((codec->width == icodec->width -
                                (frame_leftBand + frame_rightBand)) &&
                        (codec->height == icodec->height -
                                (frame_topBand  + frame_bottomBand)) &&
                                (frame_rightBand + frame_leftBand + frame_topBand + frame_bottomBand)) {
                    ost->video_resample = 0;
                    ost->video_crop = 1;
                    ost->topBand = frame_topBand;
                    ost->leftBand = frame_leftBand;
                } else if ((codec->width == icodec->width +
                                (frame_padleft + frame_padright)) &&
                        (codec->height == icodec->height +
                                (frame_padtop + frame_padbottom)) &&
                                (frame_padright + frame_padleft + frame_padtop + frame_padbottom)) {
                    ost->video_resample = 0;
                    ost->video_crop = 0;
                    ost->video_pad = 1;
                    ost->padtop = frame_padtop;
                    ost->padleft = frame_padleft;
                    ost->padbottom = frame_padbottom;
                    ost->padright = frame_padright;
                    avcodec_get_frame_defaults(&ost->pict_tmp);
                    if( avpicture_alloc( (AVPicture*)&ost->pict_tmp, PIX_FMT_YUV420P,
                                codec->width, codec->height ) )
                        goto fail;
                } else {
                    ost->video_resample = 1;
                    ost->video_crop = 0; // cropping is handled as part of resample
                    avcodec_get_frame_defaults(&ost->pict_tmp);
                    if( avpicture_alloc( (AVPicture*)&ost->pict_tmp, PIX_FMT_YUV420P,
                                         codec->width, codec->height ) )
                        goto fail;

                    ost->img_resample_ctx = img_resample_full_init(
                                      codec->width, codec->height,
                                      icodec->width, icodec->height,
                                      frame_topBand, frame_bottomBand,
                            frame_leftBand, frame_rightBand,
                            frame_padtop, frame_padbottom,
                            frame_padleft, frame_padright);

                    ost->padtop = frame_padtop;
                    ost->padleft = frame_padleft;
                    ost->padbottom = frame_padbottom;
                    ost->padright = frame_padright;

                }
                ost->encoding_needed = 1;
                ist->decoding_needed = 1;
                break;
            case CODEC_TYPE_SUBTITLE:
                ost->encoding_needed = 1;
                ist->decoding_needed = 1;
                break;
            default:
                av_abort();
                break;
            }
            /* two pass mode */
            if (ost->encoding_needed &&
                (codec->flags & (CODEC_FLAG_PASS1 | CODEC_FLAG_PASS2))) {
                char logfilename[1024];
                FILE *f;
                int size;
                char *logbuffer;

                snprintf(logfilename, sizeof(logfilename), "%s-%d.log",
                         pass_logfilename ?
                         pass_logfilename : DEFAULT_PASS_LOGFILENAME, i);
                if (codec->flags & CODEC_FLAG_PASS1) {
                    f = fopen(logfilename, "w");
                    if (!f) {
                        perror(logfilename);