ffmpeg复制保存时间戳 [英] ffmpeg copyts to preserve timestamp

问题描述

我正在尝试修改HLS段传输流，并使用ffmpeg保留其开始时间.但是，即使提到了-copyts，输出也不会保留输入文件的start_time值.这是我的命令行:

I am trying to modify an HLS segment transport stream, and preserve its start time with ffmpeg. However the output does not preserve the input file's start_time value, even if -copyts is mentioned. Here's my command line:

ffmpeg  -i fileSequence1.ts -i x.png -filter_complex '[0:v][1:v]overlay[out]' -map '[out]' -map 0:1 -acodec copy -vsync 0 -vcodec libx264 -streamid 0:257 -streamid 1:258 -copyts -profile:v baseline -level 3 output.ts

start_time值始终延迟约2秒.

The start_time value is delayed about 2 seconds consistently.

/Users/macadmin/>ffmpeg -y -v verbose -i fileSequence0.ts -map 0:0 -vcodec libx264 -copyts -vsync 0 -async 0 output.ts
ffmpeg version 2.5.3 Copyright (c) 2000-2015 the FFmpeg developers
  built on Mar 29 2015 21:31:57 with Apple LLVM version 6.0 (clang-600.0.54) (based on LLVM 3.5svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/2.5.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libfreetype --enable-libvorbis --enable-libvpx --enable-libass --enable-ffplay --enable-libfdk-aac --enable-libopus --enable-libquvi --enable-libx265 --enable-nonfree --enable-vda
  libavutil      54. 15.100 / 54. 15.100
  libavcodec     56. 13.100 / 56. 13.100
  libavformat    56. 15.102 / 56. 15.102
  libavdevice    56.  3.100 / 56.  3.100
  libavfilter     5.  2.103 /  5.  2.103
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
[h264 @ 0x7fa93b800000] Current profile doesn't provide more RBSP data in PPS, skipping
    Last message repeated 2 times
[mpegts @ 0x7fa93a80da00] max_analyze_duration 5000000 reached at 5000000 microseconds
Input #0, mpegts, from 'fileSequence0.ts':
  Duration: 00:00:09.65, start: 9.952111, bitrate: 412 kb/s
  Program 1 
    Stream #0:0[0x101]: Video: h264 (Constrained Baseline) ([27][0][0][0] / 0x001B), yuv420p, 640x360 (640x368), 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x102]: Audio: aac (LC) ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 101 kb/s
[graph 0 input from stream 0:0 @ 0x7fa93a5229c0] w:640 h:360 pixfmt:yuv420p tb:1/90000 fr:25/1 sar:0/1 sws_param:flags=2
[libx264 @ 0x7fa93b800c00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0x7fa93b800c00] profile High, level 3.0
[mpegts @ 0x7fa93b800600] muxrate VBR, pcr every 2 pkts, sdt every 200, pat/pmt every 40 pkts
Output #0, mpegts, to 'output.ts':
  Metadata:
    encoder         : Lavf56.15.102
    Stream #0:0: Video: h264 (libx264), yuv420p, 640x360, q=-1--1, 25 fps, 90k tbn, 25 tbc
    Metadata:
      encoder         : Lavc56.13.100 libx264
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[NULL @ 0x7fa93b800000] Current profile doesn't provide more RBSP data in PPS, skipping
    Last message repeated 1 times
frame=   87 fps=0.0 q=28.0 size=      91kB time=00:00:11.40 bitrate=  65.0kbits/[NULL @ 0x7fa93b800000] Current profile doesn't provide more RBSP data in PPS, skipping
frame=  152 fps=151 q=28.0 size=     204kB time=00:00:14.00 bitrate= 119.4kbits/[NULL @ 0x7fa93b800000] Current profile doesn't provide more RBSP data in PPS, skipping
frame=  224 fps=148 q=28.0 size=     306kB time=00:00:16.88 bitrate= 148.5kbits/No more output streams to write to, finishing.
frame=  240 fps=125 q=-1.0 Lsize=     392kB time=00:00:19.52 bitrate= 164.6kbits/s    
video:334kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 17.347548%
Input file #0 (fileSequence0.ts):
  Input stream #0:0 (video): 240 packets read (360450 bytes); 240 frames decoded; 
  Input stream #0:1 (audio): 0 packets read (0 bytes); 
  Total: 240 packets (360450 bytes) demuxed
Output file #0 (output.ts):
  Output stream #0:0 (video): 240 frames encoded; 240 packets muxed (342204 bytes); 
  Total: 240 packets (342204 bytes) muxed
[libx264 @ 0x7fa93b800c00] frame I:3     Avg QP:15.08  size:  7856
[libx264 @ 0x7fa93b800c00] frame P:81    Avg QP:21.03  size:  2807
[libx264 @ 0x7fa93b800c00] frame B:156   Avg QP:23.40  size:   585
[libx264 @ 0x7fa93b800c00] consecutive B-frames: 11.7%  2.5%  7.5% 78.3%
[libx264 @ 0x7fa93b800c00] mb I  I16..4: 57.4% 17.5% 25.1%
[libx264 @ 0x7fa93b800c00] mb P  I16..4:  8.0%  8.2%  1.0%  P16..4: 30.5% 11.3%  4.6%  0.0%  0.0%    skip:36.4%
[libx264 @ 0x7fa93b800c00] mb B  I16..4:  0.1%  0.1%  0.0%  B16..8: 34.6%  2.7%  0.2%  direct: 1.3%  skip:60.9%  L0:47.3% L1:49.1% BI: 3.6%
[libx264 @ 0x7fa93b800c00] 8x8 transform intra:42.2% inter:73.3%
[libx264 @ 0x7fa93b800c00] coded y,uvDC,uvAC intra: 26.2% 43.0% 6.8% inter: 5.4% 8.5% 0.1%
[libx264 @ 0x7fa93b800c00] i16 v,h,dc,p: 46% 26%  6% 21%
[libx264 @ 0x7fa93b800c00] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 50% 14% 23%  1%  2%  6%  1%  3%  1%
[libx264 @ 0x7fa93b800c00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 40% 32% 10%  3%  3%  4%  2%  5%  2%
[libx264 @ 0x7fa93b800c00] i8c dc,h,v,p: 48% 23% 26%  3%
[libx264 @ 0x7fa93b800c00] Weighted P-Frames: Y:1.2% UV:0.0%
[libx264 @ 0x7fa93b800c00] ref P L0: 71.5% 10.7% 14.8%  2.9%  0.1%
[libx264 @ 0x7fa93b800c00] ref B L0: 95.5%  4.0%  0.5%
[libx264 @ 0x7fa93b800c00] ref B L1: 96.8%  3.2%
[libx264 @ 0x7fa93b800c00] kb/s:285.17

----------- FFProbe source video
/Users/macadmin>ffprobe fileSequence0.ts
ffprobe version 2.5.3 Copyright (c) 2007-2015 the FFmpeg developers
  built on Mar 29 2015 21:31:57 with Apple LLVM version 6.0 (clang-600.0.54) (based on LLVM 3.5svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/2.5.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libfreetype --enable-libvorbis --enable-libvpx --enable-libass --enable-ffplay --enable-libfdk-aac --enable-libopus --enable-libquvi --enable-libx265 --enable-nonfree --enable-vda
  libavutil      54. 15.100 / 54. 15.100
  libavcodec     56. 13.100 / 56. 13.100
  libavformat    56. 15.102 / 56. 15.102
  libavdevice    56.  3.100 / 56.  3.100
  libavfilter     5.  2.103 /  5.  2.103
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, mpegts, from 'fileSequence0.ts':
  Duration: 00:00:09.65, start: 9.952111, bitrate: 412 kb/s
  Program 1 
    Stream #0:0[0x101]: Video: h264 (Constrained Baseline) ([27][0][0][0] / 0x001B), yuv420p, 640x360, 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x102]: Audio: aac (LC) ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 101 kb/s

------ FFPROBE result video
/Users/macadmin>ffprobe output.ts
ffprobe version 2.5.3 Copyright (c) 2007-2015 the FFmpeg developers
  built on Mar 29 2015 21:31:57 with Apple LLVM version 6.0 (clang-600.0.54) (based on LLVM 3.5svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/2.5.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libfreetype --enable-libvorbis --enable-libvpx --enable-libass --enable-ffplay --enable-libfdk-aac --enable-libopus --enable-libquvi --enable-libx265 --enable-nonfree --enable-vda
  libavutil      54. 15.100 / 54. 15.100
  libavcodec     56. 13.100 / 56. 13.100
  libavformat    56. 15.102 / 56. 15.102
  libavdevice    56.  3.100 / 56.  3.100
  libavfilter     5.  2.103 /  5.  2.103
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, mpegts, from 'output.ts':
  Duration: 00:00:09.60, start: 11.400000, bitrate: 334 kb/s
  Program 1 
    Metadata:
      service_name    : Service01
      service_provider: FFmpeg
    Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 640x360, 25 fps, 25 tbr, 90k tbn, 50 tbc

如何确保输出文件具有相同的start_time?谢谢.

How do I ensure that output file has the same start_time? Thanks.

推荐答案

我决定在源代码中进行一些挖掘，以了解正在发生的事情.

I decided to dig a little in the source to understand what's happening.

• 使用文件中每个单独流的显示时间戳(PTS)计算程序的整体开始时间.

• The overall start_time of the program is calculated by the using the presentation time stamp(PTS) of each individual stream in the file.

ffmpeg将默认的Mux解码延迟值设置为0.7秒.这是在ffmpeg_opt.c

ffmpeg sets a default Mux decode delay value of 0.7 seconds. This is set in the ffmpeg_opt.c

如果未设置"copyts"标志(在libavformat/mpegtsenc.c中)，则将此延迟值添加到每个数据包的PTS值中:

This delay value is added to the PTS value of each packet, if the "copyts" flag is not set(in libavformat/mpegtsenc.c):

if (ts->copyts < 1) {
    if (pts != AV_NOPTS_VALUE)
        pts += delay;
    if (dts != AV_NOPTS_VALUE)
        dts += delay;
}

在这种情况下，编码器将延迟值加倍:

In this case, the encoder doubles the delay value :

const uint64_t delay = 
    av_rescale(s->max_delay, 90000, AV_TIME_BASE)*2;

因此，每个数据包的PTS增加了1.4秒的时间.如果提供了"copyts"，则将其添加到输入流的时间戳值中.

Therefore, an extra 1.4 seconds get added to each packet's PTS. If "copyts" is provided, this is added to the timestamp value from the input stream.

可以使用"muxdelay"标志来覆盖此延迟；在这种情况下，延迟设置为零.

It is possible to override this delay using the "muxdelay" flag; in that case the delay gets set to zero.

现在，为什么是0.7?为什么要对mpeg ts进行两次?我希望我知道答案，大概是规范中的某个地方.但就目前而言，这是必须要做的.

Now, why 0.7? why twice in the case of mpeg ts ?I wish I know the answers, presumably it's there in the spec somewhere. But for now, this would have to do.

这篇关于ffmpeg复制保存时间戳的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！