所以我在传输流 (*.ts) 中混合了 H264 视频 + AAC 音频。为了实现均匀分布的 PCR 值，我在命令中添加了 muxrate 标签。
ffmpeg -analyzeduration 20000000 -probesize 20M -loglevel verbose -i 1135084.m4v -i 1135084.m4a -c copy -muxrate 7982K -map 0:v:0 -map 1:a:0 -metadata:s:a:0 language=eng -metadata:s:a:0 tms_track_id=169451954 TEMP0.ts
由于我们的客户需要 DVB 字幕，我们通过字幕编辑将 SRT 转换为 DVD，然后使用 ffmpeg 使用以下命令将它们编码为 DVB：
ffmpeg -analyzeduration 20000000 -probesize 20M -loglevel verbose -i TEMP0.ts -i out.da.idx -map 0 -c copy -muxrate 7992K -map 1:s -c:s:0 dvbsub -metadata:s:s:0 language=dan TEMP1.ts
这是 ffmpeg 命令的输出：
ffmpeg version git-2019-11-18-d831edc Copyright (c) 2000-2019 the FFmpeg developers
built with gcc 9.2.1 (GCC) 20191010
configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
libavutil 56. 36.100 / 56. 36.100
libavcodec 58. 62.100 / 58. 62.100
libavformat 58. 35.100 / 58. 35.100
libavdevice 58. 9.101 / 58. 9.101
libavfilter 7. 66.100 / 7. 66.100
libswscale 5. 6.100 / 5. 6.100
libswresample 3. 6.100 / 3. 6.100
libpostproc 55. 6.100 / 55. 6.100
[h264 @ 000002bf7460d400] non-existing SPS 0 referenced in buffering period
[h264 @ 000002bf7460d400] SPS unavailable in decode_picture_timing
[h264 @ 000002bf7460d400] non-existing SPS 0 referenced in buffering period
[h264 @ 000002bf7460d400] SPS unavailable in decode_picture_timing
[h264 @ 000002bf7460d400] Reinit context to 1920x1088, pix_fmt: yuv420p
[mpegts @ 000002bf7460ae00] max_analyze_duration 20000000 reached at 20000000 microseconds st:0
[mpegts @ 000002bf7460ae00] start time for stream 2 is not set in estimate_timings_from_pts
Input #0, mpegts, from 'TEMP1.ts':
Duration: 01:51:54.48, start: 1.440000, bitrate: 7992 kb/s
Program 1
Metadata:
service_name : Service01
service_provider: FFmpeg
Stream #0:0[0x100]: Video: h264 (High), 1 reference frame ([27][0][0][0] / 0x001B), yuv420p(progressive, left), 1920x1080 (1920x1088) [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
Stream #0:1[0x101](eng): Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 254 kb/s
Stream #0:2[0x102](dan): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
[vobsub @ 000002bf75d65940] IDX/SUB: out.fi.idx -> out.fi.sub
Input #1, vobsub, from 'out.fi.idx':
Duration: N/A, bitrate: N/A
Stream #1:0[0x0](fi): Subtitle: dvd_subtitle, 1920x1080 (default)
File 'TEMP2.ts' already exists. Overwrite? [y/N] y
[mpegts @ 000002bf74634f00] service 1 using PCR in pid=256, pcr_period=20ms
[mpegts @ 000002bf74634f00] muxrate 8002000, sdt every 500 ms, pat/pmt every 100 ms
Output #0, mpegts, to 'TEMP2.ts':
Metadata:
encoder : Lavf58.35.100
Stream #0:0: Video: h264 (High), 1 reference frame ([27][0][0][0] / 0x001B), yuv420p(progressive, left), 1920x1080 (0x0) [SAR 1:1 DAR 16:9], q=2-31, 25 fps, 25 tbr, 90k tbn, 90k tbc
Stream #0:1(eng): Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 254 kb/s
Stream #0:2(dan): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
Stream #0:3(fin): Subtitle: dvb_subtitle (dvbsub), 1920x1080 (default)
Metadata:
encoder : Lavc58.62.100 dvbsub
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (copy)
Stream #0:2 -> #0:2 (copy)
Stream #1:0 -> #0:3 (dvd_subtitle (dvdsub) -> dvb_subtitle (dvbsub))
Press [q] to stop, [?] for help
No more output streams to write to, finishing.me=01:51:46.51 bitrate=7990.2kbits/s speed=18.2x
frame=167862 fps=456 q=-1.0 Lsize= 6558750kB time=01:51:54.47 bitrate=8002.0kbits/s speed=18.2x
video:5738580kB audio:212004kB subtitle:10989kB other streams:0kB global headers:0kB muxing overhead: 10.017118%
Input file #0 (TEMP1.ts):
Input stream #0:0 (video): 167862 packets read (5876305439 bytes);
Input stream #0:1 (audio): 314742 packets read (217092443 bytes);
Input stream #0:2 (subtitle): 1740 packets read (5578504 bytes);
Total: 484344 packets (6098976386 bytes) demuxed
Input file #1 (out.fi.idx):
Input stream #1:0 (subtitle): 855 packets read (6881158 bytes); 854 frames decoded;
Total: 855 packets (6881158 bytes) demuxed
Output file #0 (TEMP2.ts):
Output stream #0:0 (video): 167862 packets muxed (5876305439 bytes);
Output stream #0:1 (audio): 314742 packets muxed (217092443 bytes);
Output stream #0:2 (subtitle): 1740 packets muxed (5578504 bytes);
Output stream #0:3 (subtitle): 1708 frames encoded; 1708 packets muxed (5673736 bytes);
Total: 486052 packets (6104650122 bytes) muxed
[AVIOContext @ 000002bf7463c280] Statistics: 0 seeks, 25621 writeouts
[AVIOContext @ 000002bf74613f80] Statistics: 6728300448 bytes read, 2 seeks
[AVIOContext @ 000002bf75efde40] Statistics: 7852032 bytes read, 0 seeks
[AVIOContext @ 000002bf74f30e40] Statistics: 40275 bytes read, 0 seeks
所以我在一个 TS 中有视频/音频和两个 dvb 轨道。
现在我添加了第三个字幕，我收到了这个警告：
frame=32351 fps=869 q=-1.0 size= 1255936kB time=00:21:33.99 bitrate=7951.1kbits/s speed=34.8x
[mpegts @ 0x2994600] Non-monotonous DTS in output stream 0:3; previous: 116868609, current: 116868607; changing to 116868610. This may result in incorrect timestamps in the output file.
frame=33416 fps=886 q=-1.0 size= 1297408kB time=00:22:16.56 bitrate=7952.0kbits/s speed=35.4x
通过这个警告，DVB (0:3) 完成轨道似乎有些不对劲。用 VLC 播放文件我可以看到完成字幕（21:33 到 22:16 之间）没有出现。
从 0:3 轨道转储数据包我看到 4 个数据包具有相同的 DTS/PTS 值。
#stream#, dts, pts, duration, size, hash
0, 111258000, 111258000, 0, 6979, 6215f060, S=1, 1, 67d220bc
0, 111689100, 111689100, 0, 25, e60e94fa, S=1, 1, 67d220bc
0, 113230800, 113230800, 0, 4423, f811be62, S=1, 1, 67d220bc
0, 113561550, 113561550, 0, 25, 6db8d81f, S=1, 1, 67d220bc
0, 113788800, 113788800, 0, 8247, 8b494779, S=1, 1, 67d220bc
0, 114191190, 114191190, 0, 25, a205e183, S=1, 1, 67d220bc
0, 116868607, 116868607, 0, 1119, e5d11188, S=1, 1, 67d220bc
0, 116868607, 116868607, 0, 28, 11e09861, S=1, 1, 67d220bc
0, 116868607, 116868607, 0, 1122, 8320a3f5, S=1, 1, 67d220bc
0, 116868607, 116868607, 0, 28, e896fa37, S=1, 1, 67d220bc
0, 117205200, 117205200, 0, 3583, 47b23f27, S=1, 1, 67d220bc
0, 117611640, 117611640, 0, 25, e5ae32ed, S=1, 1, 67d220bc
0, 117709200, 117709200, 0, 1119, 208b4f80, S=1, 1, 67d220bc
0, 117830970, 117830970, 0, 25, 2a130b71, S=1, 1, 67d220bc
0, 117846000, 117846000, 0, 3105, f179a4f0, S=1, 1, 67d220bc
0, 118148040, 118148040, 0, 25, 29b3ad66, S=1, 1, 67d220bc
0, 120146410, 120146410, 0, 1119, 714ef5d1, S=1, 1, 67d220bc
0, 120146410, 120146410, 0, 28, bbad7fed, S=1, 1, 67d220bc
0, 120708000, 120708000, 0, 2060, 703084f7, S=1, 1, 67d220bc
0, 120855420, 120855420, 0, 25, 6db8d81f, S=1, 1, 67d220bc
0, 121122000, 121122000, 0, 2184, 04a7be71, S=1, 1, 67d220bc
0, 121395330, 121395330, 0, 25, a205e183, S=1, 1, 67d220bc
这些是 SRT 文件中发生警告的行：
146
00:21:34,840 --> 00:21:36,600
Make!
147
00:21:42,280 --> 00:21:46,800
Make! Hei, Make. Make!
148
00:21:47,880 --> 00:21:49,240
Make!
149
00:21:49,400 --> 00:21:52,760
Odota minua, Make!
150
00:22:00,400 --> 00:22:01,760
Make!
有时以不同的顺序混合字幕（例如在丹麦语和瑞典语之前完成）可以解决这个问题，但我想知道为什么会发生这样的事情。