ffmpeg 中print_report中相關日誌說明
原文：https://my.oschina.net/u/2326611/blog/679993
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輸出幀率設的比輸入幀率大，沒意義，除非有好的插幀算法； 比輸入幀率小，出畫面的速度就會變慢， 意味着需要主動丟棄掉一些幀，以此來降低輸出幀率。
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: 編碼的幀數量
fps：每秒編碼的幀數
q：質量因子
size：視頻和音頻編碼後的大小(個人理解)，即 Lsize= 566kB ，基本等於 video:397kB 和audio:160kB 之和
time：輸出幀的顯示時間
bitrate：輸出視頻的幀率
dup：輸入幀dupliate的數量
drop：輸入幀drop的個數
speed：編碼速度這個speed在ffmpeg源碼中定義,見ffmpeg 3.0 中 print_report 源碼：
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);
}
因爲源流的輸入幀率爲15，輸出幀率爲10。所以輸入幀數和輸出幀數的比例爲1.5:1.
從日誌看出輸入解碼幀爲155，輸出編碼幀104，即丟棄51幀，所以比例基本爲1.5:1。
=======
一轉一日誌
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 bytes
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
video: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) demuxed
Output 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) muxed
597 frames successfully decoded, 0 decoding errors
因爲源流的輸入幀率爲15，輸出幀率爲10。所以輸入幀數和輸出幀數的比例爲1.5:1.
從日誌看出輸入解碼幀爲155，輸出編碼幀104，即丟棄51幀，所以比例基本爲1.5:1。