ffmpeg 中print_report中相关日志说明

ffmpeg 中print_report中相关日志说明

 原文：https://my.oschina.net/u/2326611/blog/679993

 推荐流媒体相关学习文章列表： http://www.cnblogs.com/my_life/category/282307.html

       输出帧率设的比输入帧率大，没意义，除非有好的插帧算法； 比输入帧率小，出画面的速度就会变慢， 意味着需要主动丢弃掉一些帧，以此来降低输出帧率。

frame=  104 fps= 57 q=26.0 Lsize=     566kB time=00:00:10.30 bitrate= 450.5kbits/s dup=0 drop=50 speed=5.68x

frame: 编码的帧数量fps：每秒编码的帧数q：质量因子size：视频和音频编码后的大小(个人理解)，即 Lsize=     566kB ，基本等于 video:397kB 和audio:160kB 之和time：输出帧的显示时间bitrate：输出视频的帧率dup：输入帧dupliate的数量drop：输入帧drop的个数speed：编码速度

这个speed在ffmpeg源码中定义,见ffmpeg 3.0 中 print_report 源码：

static void print_report(int is_last_report, int64_t timer_start, int64_t cur_time){    char buf[1024];    AVBPrint buf_script;    OutputStream *ost;    AVFormatContext *oc;    int64_t total_size;    AVCodecContext *enc;    int frame_number, vid, i;    double bitrate;    double speed;    int64_t pts = INT64_MIN + 1;    static int64_t last_time = -1;    static int qp_histogram[52];    int hours, mins, secs, us;    int ret;    float t;    if (!print_stats && !is_last_report && !progress_avio)        return;    if (!is_last_report) {        if (last_time == -1) {            last_time = cur_time;            return;        }        if ((cur_time - last_time) < 500000)            return;        last_time = cur_time;    }    t = (cur_time-timer_start) / 1000000.0;    oc = output_files[0]->ctx;    total_size = avio_size(oc->pb);    if (total_size <= 0) // FIXME improve avio_size() so it works with non seekable output too        total_size = avio_tell(oc->pb);    buf[0] = '\0';    vid = 0;    av_bprint_init(&buf_script, 0, 1);    for (i = 0; i < nb_output_streams; i++) {        float q = -1;        ost = output_streams[i];        enc = ost->enc_ctx;        if (!ost->stream_copy)            q = ost->quality / (float) FF_QP2LAMBDA;        if (vid && enc->codec_type == AVMEDIA_TYPE_VIDEO) {            snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "q=%2.1f ", q);            av_bprintf(&buf_script, "stream_%d_%d_q=%.1f\n",                       ost->file_index, ost->index, q);        }        if (!vid && enc->codec_type == AVMEDIA_TYPE_VIDEO) {            float fps;            frame_number = ost->frame_number;            fps = t > 1 ? frame_number / t : 0;            snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "frame=%5d fps=%3.*f q=%3.1f ",                     frame_number, fps < 9.95, fps, q);            av_bprintf(&buf_script, "frame=%d\n", frame_number);            av_bprintf(&buf_script, "fps=%.1f\n", fps);            av_bprintf(&buf_script, "stream_%d_%d_q=%.1f\n",                       ost->file_index, ost->index, q);            if (is_last_report)                snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "L");            if (qp_hist) {                int j;                int qp = lrintf(q);                if (qp >= 0 && qp < FF_ARRAY_ELEMS(qp_histogram))                    qp_histogram[qp]++;                for (j = 0; j < 32; j++)                    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "%X", av_log2(qp_histogram[j] + 1));            }            if ((enc->flags & AV_CODEC_FLAG_PSNR) && (ost->pict_type != AV_PICTURE_TYPE_NONE || is_last_report)) {                int j;                double error, error_sum = 0;                double scale, scale_sum = 0;                double p;                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 = ost->error[j];                        scale = enc->width * enc->height * 255.0 * 255.0;                    }                    if (j)                        scale /= 4;                    error_sum += error;                    scale_sum += scale;                    p = psnr(error / scale);                    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "%c:%2.2f ", type[j], p);                    av_bprintf(&buf_script, "stream_%d_%d_psnr_%c=%2.2f\n",                               ost->file_index, ost->index, type[j] | 32, p);                }                p = psnr(error_sum / scale_sum);                snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "*:%2.2f ", psnr(error_sum / scale_sum));                av_bprintf(&buf_script, "stream_%d_%d_psnr_all=%2.2f\n",                           ost->file_index, ost->index, p);            }            vid = 1;        }        /* compute min output value */        if (av_stream_get_end_pts(ost->st) != AV_NOPTS_VALUE)            pts = FFMAX(pts, av_rescale_q(av_stream_get_end_pts(ost->st),                                          ost->st->time_base, AV_TIME_BASE_Q));        if (is_last_report)            nb_frames_drop += ost->last_dropped;    }    secs = FFABS(pts) / AV_TIME_BASE;    us = FFABS(pts) % AV_TIME_BASE;    mins = secs / 60;    secs %= 60;    hours = mins / 60;    mins %= 60;    bitrate = pts && total_size >= 0 ? total_size * 8 / (pts / 1000.0) : -1;    speed = t != 0.0 ? (double)pts / AV_TIME_BASE / t : -1;    if (total_size < 0) snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf),                                 "size=N/A time=");    else                snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf),                                 "size=%8.0fkB time=", total_size / 1024.0);    if (pts < 0)        snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "-");    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf),             "%02d:%02d:%02d.%02d ", hours, mins, secs,             (100 * us) / AV_TIME_BASE);    if (bitrate < 0) {        snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf),"bitrate=N/A");        av_bprintf(&buf_script, "bitrate=N/A\n");    }else{        snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf),"bitrate=%6.1fkbits/s", bitrate);        av_bprintf(&buf_script, "bitrate=%6.1fkbits/s\n", bitrate);    }    if (total_size < 0) av_bprintf(&buf_script, "total_size=N/A\n");    else                av_bprintf(&buf_script, "total_size=%"PRId64"\n", total_size);    av_bprintf(&buf_script, "out_time_ms=%"PRId64"\n", pts);    av_bprintf(&buf_script, "out_time=%02d:%02d:%02d.%06d\n",               hours, mins, secs, us);    if (nb_frames_dup || nb_frames_drop)        snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), " dup=%d drop=%d",                nb_frames_dup, nb_frames_drop);    av_bprintf(&buf_script, "dup_frames=%d\n", nb_frames_dup);    av_bprintf(&buf_script, "drop_frames=%d\n", nb_frames_drop);    if (speed < 0) {        snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf)," speed=N/A");        av_bprintf(&buf_script, "speed=N/A\n");    } else {        snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf)," speed=%4.3gx", speed);        av_bprintf(&buf_script, "speed=%4.3gx\n", speed);    }    if (print_stats || is_last_report) {        const char end = is_last_report ? '\n' : '\r';        if (print_stats==1 && AV_LOG_INFO > av_log_get_level()) {            fprintf(stderr, "%s    %c", buf, end);        } else            av_log(NULL, AV_LOG_INFO, "%s    %c", buf, end);    fflush(stderr);    }    if (progress_avio) {        av_bprintf(&buf_script, "progress=%s\n",                   is_last_report ? "end" : "continue");        avio_write(progress_avio, buf_script.str,                   FFMIN(buf_script.len, buf_script.size - 1));        avio_flush(progress_avio);        av_bprint_finalize(&buf_script, NULL);        if (is_last_report) {            if ((ret = avio_closep(&progress_avio)) < 0)                av_log(NULL, AV_LOG_ERROR,                       "Error closing progress log, loss of information possible: %s\n", av_err2str(ret));        }    }    if (is_last_report)        print_final_stats(total_size);} 

因为源流的输入帧率为15，输出帧率为10。所以输入帧数和输出帧数的比例为1.5:1.

从日志看出输入解码帧为155，输出编码帧104，即丢弃51帧，所以比例基本为1.5:1。

=======

一转一日志

例如：

./ffmpeg -i test_2.flv -vcodec libx264 -b:v 300000 -r 10 -report -y -f flv test_1out.flv

 

frame=   58 fps=0.0 q=26.0 size=      98kB time=00:00:05.61 bitrate= 142.9kbits/s dup=0 drop=27 speed=11.2x... ...frame=   85 fps= 84 q=25.0 size=     222kB time=00:00:08.30 bitrate= 218.7kbits/s dup=0 drop=41 speed=8.25x... ...[libx264 @ 0x3a7c540] frame= 103 QP=24.06 NAL=2 Slice:P Poc:4   I:1    P:58   SKIP:1005 size=216 bytesframe=  104 fps= 57 q=26.0 Lsize=     566kB time=00:00:10.30 bitrate= 450.5kbits/s dup=0 drop=50 speed=5.68xvideo:397kB audio:160kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.571039%Input file #0 (test_2.flv):  Input stream #0:0 (video): 156 packets read (684497 bytes); 155 frames decoded;  Input stream #0:1 (audio): 443 packets read (82827 bytes); 442 frames decoded (452608 samples);  Total: 599 packets (767324 bytes) demuxedOutput file #0 (test_1out.flv):  Output stream #0:0 (video): 104 frames encoded; 104 packets muxed (406830 bytes);  Output stream #0:1 (audio): 392 frames encoded (451584 samples); 393 packets muxed (164257 bytes);  Total: 497 packets (571087 bytes) muxed597 frames successfully decoded, 0 decoding errors

 

因为源流的输入帧率为15，输出帧率为10。所以输入帧数和输出帧数的比例为1.5:1.

从日志看出输入解码帧为155，输出编码帧104，即丢弃51帧，所以比例基本为1.5:1。