ffmpeg.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

    enc = ost->st->codec;
    dec = ist->st->codec;

    /* by default, we output a single frame */
    nb_frames = 1;

    *frame_size = 0;

    if(video_sync_method){
        double vdelta;
        vdelta = get_sync_ipts(ost) / av_q2d(enc->time_base) - ost->sync_opts;
        //FIXME set to 0.5 after we fix some dts/pts bugs like in avidec.c
        if (vdelta < -1.1)
            nb_frames = 0;
        else if (vdelta > 1.1)
            nb_frames = lrintf(vdelta);
//fprintf(stderr, "vdelta:%f, ost->sync_opts:%"PRId64", ost->sync_ipts:%f nb_frames:%d\n", vdelta, ost->sync_opts, ost->sync_ipts, nb_frames);
        if (nb_frames == 0){
            ++nb_frames_drop;
            if (verbose>2)
                fprintf(stderr, "*** drop!\n");
        }else if (nb_frames > 1) {
            nb_frames_dup += nb_frames;
            if (verbose>2)
                fprintf(stderr, "*** %d dup!\n", nb_frames-1);
        }
    }else
        ost->sync_opts= lrintf(get_sync_ipts(ost) / av_q2d(enc->time_base));

    nb_frames= FFMIN(nb_frames, max_frames[CODEC_TYPE_VIDEO] - ost->frame_number);
    if (nb_frames <= 0)
        return;

    if (ost->video_crop) {
        if (av_picture_crop((AVPicture *)&picture_crop_temp, (AVPicture *)in_picture, dec->pix_fmt, ost->topBand, ost->leftBand) < 0) {
            av_log(NULL, AV_LOG_ERROR, "error cropping picture\n");
            return;
        }
        formatted_picture = &picture_crop_temp;
    } else {
        formatted_picture = in_picture;
    }

    final_picture = formatted_picture;
    padding_src = formatted_picture;
    resampling_dst = &ost->pict_tmp;
    if (ost->video_pad) {
        final_picture = &ost->pict_tmp;
        if (ost->video_resample) {
            if (av_picture_crop((AVPicture *)&picture_pad_temp, (AVPicture *)final_picture, enc->pix_fmt, ost->padtop, ost->padleft) < 0) {
                av_log(NULL, AV_LOG_ERROR, "error padding picture\n");
                return;
            }
            resampling_dst = &picture_pad_temp;
        }
    }

    if (ost->video_resample) {
        padding_src = NULL;
        final_picture = &ost->pict_tmp;
        sws_scale(ost->img_resample_ctx, formatted_picture->data, formatted_picture->linesize,
              0, ost->resample_height, resampling_dst->data, resampling_dst->linesize);
    }

    if (ost->video_pad) {
        av_picture_pad((AVPicture*)final_picture, (AVPicture *)padding_src,
                enc->height, enc->width, enc->pix_fmt,
                ost->padtop, ost->padbottom, ost->padleft, ost->padright, padcolor);
    }

    /* duplicates frame if needed */
    for(i=0;i<nb_frames;i++) {
        AVPacket pkt;
        av_init_packet(&pkt);
        pkt.stream_index= ost->index;

        if (s->oformat->flags & AVFMT_RAWPICTURE) {
            /* raw pictures are written as AVPicture structure to
               avoid any copies. We support temorarily the older
               method. */
            AVFrame* old_frame = enc->coded_frame;
            enc->coded_frame = dec->coded_frame; //FIXME/XXX remove this hack
            pkt.data= (uint8_t *)final_picture;
            pkt.size=  sizeof(AVPicture);
            if(dec->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);
            if(dec->coded_frame && dec->coded_frame->key_frame)
                pkt.flags |= PKT_FLAG_KEY;

            write_frame(s, &pkt, ost->st->codec, bitstream_filters[ost->file_index][pkt.stream_index]);
            enc->coded_frame = old_frame;
        } else {
            AVFrame big_picture;

            big_picture= *final_picture;
            /* better than nothing: use input picture interlaced
               settings */
            big_picture.interlaced_frame = in_picture->interlaced_frame;
            if(avctx_opts[CODEC_TYPE_VIDEO]->flags & (CODEC_FLAG_INTERLACED_DCT|CODEC_FLAG_INTERLACED_ME)){
                if(top_field_first == -1)
                    big_picture.top_field_first = in_picture->top_field_first;
                else
                    big_picture.top_field_first = top_field_first;
            }

            /* handles sameq here. This is not correct because it may
               not be a global option */
            if (same_quality) {
                big_picture.quality = ist->st->quality;
            }else
                big_picture.quality = ost->st->quality;
            if(!me_threshold)
                big_picture.pict_type = 0;
//            big_picture.pts = AV_NOPTS_VALUE;
            big_picture.pts= ost->sync_opts;
//            big_picture.pts= av_rescale(ost->sync_opts, AV_TIME_BASE*(int64_t)enc->time_base.num, enc->time_base.den);
//av_log(NULL, AV_LOG_DEBUG, "%"PRId64" -> encoder\n", ost->sync_opts);
            ret = avcodec_encode_video(enc,
                                       bit_buffer, bit_buffer_size,
                                       &big_picture);
            if (ret == -1) {
                fprintf(stderr, "Video encoding failed\n");
                exit(1);
            }
            //enc->frame_number = enc->real_pict_num;
            if(ret>0){
                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_log(NULL, AV_LOG_DEBUG, "encoder -> %"PRId64"/%"PRId64"\n",
   pkt.pts != AV_NOPTS_VALUE ? av_rescale(pkt.pts, enc->time_base.den, AV_TIME_BASE*(int64_t)enc->time_base.num) : -1,
   pkt.dts != AV_NOPTS_VALUE ? av_rescale(pkt.dts, enc->time_base.den, AV_TIME_BASE*(int64_t)enc->time_base.num) : -1);*/

                if(enc->coded_frame && enc->coded_frame->key_frame)
                    pkt.flags |= PKT_FLAG_KEY;
                write_frame(s, &pkt, ost->st->codec, bitstream_filters[ost->file_index][pkt.stream_index]);
                *frame_size = ret;
                //fprintf(stderr,"\nFrame: %3d %3d size: %5d type: %d",
                //        enc->frame_number-1, enc->real_pict_num, ret,
                //        enc->pict_type);
                /* if two pass, output log */
                if (ost->logfile && enc->stats_out) {
                    fprintf(ost->logfile, "%s", enc->stats_out);
                }
            }
        }
        ost->sync_opts++;
        ost->frame_number++;
    }
}

static double psnr(double d){
    if(d==0) return INFINITY;
    return -10.0*log(d)/log(10.0);
}

static void do_video_stats(AVFormatContext *os, AVOutputStream *ost,
                           int frame_size)
{
    AVCodecContext *enc;
    int frame_number;
    double ti1, bitrate, avg_bitrate;

    /* this is executed just the first time do_video_stats is called */
    if (!vstats_file) {
        vstats_file = fopen(vstats_filename, "w");
        if (!vstats_file) {
            perror("fopen");
            exit(1);
        }
    }

    enc = ost->st->codec;
    if (enc->codec_type == CODEC_TYPE_VIDEO) {
        frame_number = ost->frame_number;
        fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);
        if (enc->flags&CODEC_FLAG_PSNR)
            fprintf(vstats_file, "PSNR= %6.2f ", psnr(enc->coded_frame->error[0]/(enc->width*enc->height*255.0*255.0)));

        fprintf(vstats_file,"f_size= %6d ", frame_size);
        /* compute pts value */
        ti1 = ost->sync_opts * av_q2d(enc->time_base);
        if (ti1 < 0.01)
            ti1 = 0.01;

        bitrate = (frame_size * 8) / av_q2d(enc->time_base) / 1000.0;
        avg_bitrate = (double)(video_size * 8) / ti1 / 1000.0;
        fprintf(vstats_file, "s_size= %8.0fkB time= %0.3f br= %7.1fkbits/s avg_br= %7.1fkbits/s ",
            (double)video_size / 1024, ti1, bitrate, avg_bitrate);
        fprintf(vstats_file,"type= %c\n", av_get_pict_type_char(enc->coded_frame->pict_type));
    }
}

static void print_report(AVFormatContext **output_files,
                         AVOutputStream **ost_table, int nb_ostreams,
                         int is_last_report)
{
    char buf[1024];
    AVOutputStream *ost;
    AVFormatContext *oc, *os;
    int64_t total_size;
    AVCodecContext *enc;
    int frame_number, vid, i;
    double bitrate, ti1, pts;
    static int64_t last_time = -1;
    static int qp_histogram[52];

    if (!is_last_report) {
        int64_t cur_time;
        /* display the report every 0.5 seconds */
        cur_time = av_gettime();
        if (last_time == -1) {
            last_time = cur_time;
            return;
        }
        if ((cur_time - last_time) < 500000)
            return;
        last_time = cur_time;
    }


    oc = output_files[0];

    total_size = url_fsize(&oc->pb);
    if(total_size<0) // FIXME improve url_fsize() so it works with non seekable output too
        total_size= url_ftell(&oc->pb);

    buf[0] = '\0';
    ti1 = 1e10;
    vid = 0;
    for(i=0;i<nb_ostreams;i++) {
        ost = ost_table[i];
        os = output_files[ost->file_index];
        enc = ost->st->codec;
        if (vid && enc->codec_type == CODEC_TYPE_VIDEO) {
            snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "q=%2.1f ",
                    enc->coded_frame->quality/(float)FF_QP2LAMBDA);
        }
        if (!vid && enc->codec_type == CODEC_TYPE_VIDEO) {
            float t = (av_gettime()-timer_start) / 1000000.0;

            frame_number = ost->frame_number;
            snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "frame=%5d fps=%3d q=%3.1f ",
                     frame_number, (t>1)?(int)(frame_number/t+0.5) : 0,
                     enc->coded_frame ? enc->coded_frame->quality/(float)FF_QP2LAMBDA : -1);
            if(is_last_report)
                snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "L");
            if(qp_hist && enc->coded_frame){
                int j;
                int qp= lrintf(enc->coded_frame->quality/(float)FF_QP2LAMBDA);
                if(qp>=0 && qp<sizeof(qp_histogram)/sizeof(int))
                    qp_histogram[qp]++;
                for(j=0; j<32; j++)
                    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "%X", (int)lrintf(log(qp_histogram[j]+1)/log(2)));
            }
            if (enc->flags&CODEC_FLAG_PSNR){
                int j;
                double error, error_sum=0;
                double scale, scale_sum=0;
                char type[3]= {'Y','U','V'};
                snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "PSNR=");
                for(j=0; j<3; j++){
                    if(is_last_report){
                        error= enc->error[j];
                        scale= enc->width*enc->height*255.0*255.0*frame_number;
                    }else{
                        error= enc->coded_frame->error[j];
                        scale= enc->width*enc->height*255.0*255.0;
                    }
                    if(j) scale/=4;
                    error_sum += error;
                    scale_sum += scale;
                    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "%c:%2.2f ", type[j], psnr(error/scale));
                }
                snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "*:%2.2f ", psnr(error_sum/scale_sum));
            }
            vid = 1;
        }
        /* compute min output value */
        pts = (double)ost->st->pts.val * av_q2d(ost->st->time_base);
        if ((pts < ti1) && (pts > 0))
            ti1 = pts;
    }
    if (ti1 < 0.01)
        ti1 = 0.01;

    if (verbose || is_last_report) {
        bitrate = (double)(total_size * 8) / ti1 / 1000.0;

        snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf),
            "size=%8.0fkB time=%0.1f bitrate=%6.1fkbits/s",
            (double)total_size / 1024, ti1, bitrate);

        if (verbose > 1)
          snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), " dup=%d drop=%d",
                  nb_frames_dup, nb_frames_drop);

        if (verbose >= 0)
            fprintf(stderr, "%s    \r", buf);

        fflush(stderr);
    }

    if (is_last_report && verbose >= 0){
        int64_t raw= audio_size + video_size + extra_size;
        fprintf(stderr, "\n");
        fprintf(stderr, "video:%1.0fkB audio:%1.0fkB global headers:%1.0fkB muxing overhead %f%%\n",
                video_size/1024.0,
                audio_size/1024.0,
                extra_size/1024.0,
                100.0*(total_size - raw)/raw
        );
    }
}

/* pkt = NULL means EOF (needed to flush decoder buffers) */
static int output_packet(AVInputStream *ist, int ist_index,
                         AVOutputStream **ost_table, int nb_ostreams,
                         const AVPacket *pkt)
{
    AVFormatContext *os;
    AVOutputStream *ost;
    uint8_t *ptr;
    int len, ret, i;
    uint8_t *data_buf;
    int data_size, got_picture;
    AVFrame picture;
    void *buffer_to_free;
    static unsigned int samples_size= 0;
    static short *samples= NULL;
    AVSubtitle subtitle, *subtitle_to_free;
    int got_subtitle;

    if(!pkt){
        ist->pts= ist->next_pts; // needed for last packet if vsync=0
    } else if (pkt->dts != AV_NOPTS_VALUE) { //FIXME seems redundant, as libavformat does this too
        ist->next_pts = ist->pts = av_rescale_q(pkt->dts, ist->st->time_base, AV_TIME_BASE_Q);
    } else {
//        assert(ist->pts == ist->next_pts);
    }

    if (pkt == NULL) {
        /* EOF handling */
        ptr = NULL;
        len = 0;