我正在尝试将视频分割成 GOP（非固定大小），然后分别对视频的每个部分（GOP）进行转码。我正在尝试使用 HLS（HTTP 流协议），因此这些视频块是 MPEG2-TS（.ts）。
看来分割视频工作正常，我创建了清单 (.m3u8) 文件，它在 VLC 上运行良好。但是，在对视频进行转码后，似乎在片段转换上产生了问题，出现了某种延迟（灰屏）。
这是我用来分割视频的命令
ffmpeg.exe -i videotest.mp4 -vcodec copy -reset_timestamps 1 -map 0 -hls_list_size 0 out.m3u8
此命令将视频分成 10 个部分（.ts 文件）并生成清单文件（.m3u8）
这是输出：
ffmpeg version N-81045-g450cf40 Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 5.4.0 (GCC)
configuration: --disable-static --enable-shared --enable-gpl --enable-
version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-
nvenc --enable-avisynth --enable-bzlib --enable-libebur128 --enable-
fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-
libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-
libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-
libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-
libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-
librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr -
-enable-libspeex --enable-libtheora --enable-libtwolame --enable-
libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx
--enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265
--enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --
enable-decklink --enable-zlib
libavutil 55. 28.100 / 55. 28.100
libavcodec 57. 50.100 / 57. 50.100
libavformat 57. 42.100 / 57. 42.100
libavdevice 57. 0.102 / 57. 0.102
libavfilter 6. 47.100 / 6. 47.100
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 1.100 / 2. 1.100
libpostproc 54. 0.100 / 54. 0.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'videotest.mp4':
Metadata:
major_brand : mp42
minor_version : 512
compatible_brands: isomiso2avc1mp41
creation_time : 2015-09-03 15:02:55
title : Fantastic Four: Rise of the Silver Surfer - Theatrical Trailer
artist : 20th Century Fox
date : 2007
encoder : HandBrake 0.10.2 2015061100
genre : Trailer
Duration: 00:00:25.07, start: 0.000000, bitrate: 1884 kb/s
Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 1280x544 [SAR 1:1 DAR 40:17], 1742 kb/s, 23.90 fps, 23.98 tbr, 90k tbn, 180k tbc (default)
Metadata:
creation_time : 2015-09-03 15:02:55
handler_name : VideoHandler
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 135 kb/s (default)
Metadata:
creation_time : 2015-09-03 15:02:55
handler_name : Stereo
[hls @ 000000000127c340] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
Last message repeated 1 times
Output #0, hls, to 'out.m3u8':
Metadata:
major_brand : mp42
minor_version : 512
compatible_brands: isomiso2avc1mp41
genre : Trailer
title : Fantastic Four: Rise of the Silver Surfer - Theatrical Trailer
artist : 20th Century Fox
date : 2007
encoder : Lavf57.42.100
Stream #0:0(und): Video: h264 (avc1 / 0x31637661), yuv420p(tv, bt709), 1280x544 [SAR 1:1 DAR 40:17], q=2-31, 1742 kb/s, 23.90 fps, 23.98 tbr, 90k tbn, 90k tbc (default)
Metadata:
creation_time : 2015-09-03 15:02:55
handler_name : VideoHandler
Stream #0:1(und): Audio: aac (LC), 48000 Hz, stereo, fltp, 128 kb/s (default)
Metadata:
creation_time : 2015-09-03 15:02:55
handler_name : Stereo
encoder : Lavc57.50.100 aac
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored bitrate=N/A speed=29.3x
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
frame= 599 fps=0.0 q=-1.0 Lsize=N/A time=00:00:25.02 bitrate=N/A speed= 29x
video:5333kB audio:314kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
[aac @ 000000000127f620] Qavg: 17473.217
到目前为止，如果我运行 m3u8 文件，它可以正常工作。
这是我用来对视频的每个片段进行编码的命令
ffmpeg.exe -i segment0.ts -vcodec libx264 -s 640:480 -map 0 outputEncoded0.ts
我使用脚本为每个段运行此命令：
#/bin/bash
SAVEIFS=$IFS
IFS=$(echo -en "\n\b")
for file in /home/pi/Desktop/videoExamples/videosTranscode/*;
do
echo "doing stuff"
filename="${file##*/}"
filename="${filename%.*}"
ffmpeg.exe -i $file -vcodec libx264 -s 640:480 -map 0 $filename.ts
done
IFS=SAVEIFS
输出如下
ffmpeg version N-81045-g450cf40 Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 5.4.0 (GCC)
configuration: --disable-static --enable-shared --enable-gpl --enable-
version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-
nvenc --enable-avisynth --enable-bzlib --enable-libebur128 --enable-
fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-
libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-
libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-
libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-
libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-
librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr -
-enable-libspeex --enable-libtheora --enable-libtwolame --enable-
libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx
--enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265
--enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --
enable-decklink --enable-zlib
libavutil 55. 28.100 / 55. 28.100
libavcodec 57. 50.100 / 57. 50.100
libavformat 57. 42.100 / 57. 42.100
libavdevice 57. 0.102 / 57. 0.102
libavfilter 6. 47.100 / 6. 47.100
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 1.100 / 2. 1.100
libpostproc 54. 0.100 / 54. 0.100
Input #0, mpegts, from 'out0.ts':
Duration: 00:00:05.69, start: 1.503789, bitrate: 215 kb/s
Program 1
Metadata:
service_name : Fantastic Four: Rise of the Silver Surfer - Theatrical Trailer
service_provider: FFmpeg
Stream #0:0[0x100]: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709), 1280x544 [SAR 1:1 DAR 40:17], 23.98 tbr, 90k tbn, 180k tbc
Stream #0:1[0x101]: Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 11 kb/s
fixme:msvcrt:MSVCRT__wsopen_s : pmode 0x01b6 ignored
[libx264 @ 0000000001244ae0] using SAR=30/17
[libx264 @ 0000000001244ae0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
[libx264 @ 0000000001244ae0] profile High, level 3.0
[mpegts @ 00000000012433e0] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
Last message repeated 1 times
Output #0, mpegts, to 'outputEncoded0.ts':
Metadata:
encoder : Lavf57.42.100
Stream #0:0: Video: h264 (libx264), yuv420p, 640x480 [SAR 30:17 DAR 40:17], q=-1--1, 23.98 fps, 90k tbn, 23.98 tbc
Metadata:
encoder : Lavc57.50.100 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
Stream #0:1: Audio: mp2, 48000 Hz, stereo, s16, 384 kb/s
Metadata:
encoder : Lavc57.50.100 mp2
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
Stream #0:1 -> #0:1 (aac (native) -> mp2 (native))
Press [q] to stop, [?] for help
frame= 116 fps=0.0 q=28.0 size= 174kB time=00:00:04.90 bitrate= 291.0kbits/frame= 135 fps=0.0 q=-1.0 Lsize= 344kB time=00:00:05.60 bitrate= 503.0kbits/s speed=7.82x
video:28kB audio:263kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 18.113007%
[libx264 @ 0000000001244ae0] frame I:1 Avg QP:15.64 size: 16539
[libx264 @ 0000000001244ae0] frame P:36 Avg QP:13.14 size: 201
[libx264 @ 0000000001244ae0] frame B:98 Avg QP:18.22 size: 52
[libx264 @ 0000000001244ae0] consecutive B-frames: 3.0% 0.0% 2.2% 94.8%
[libx264 @ 0000000001244ae0] mb I I16..4: 21.8% 65.8% 12.3%
[libx264 @ 0000000001244ae0] mb P I16..4: 0.7% 1.9% 0.0% P16..4: 2.1% 0.2% 0.1% 0.0% 0.0% skip:95.0%
[libx264 @ 0000000001244ae0] mb B I16..4: 0.0% 0.2% 0.0% B16..8: 1.7% 0.0% 0.0% direct: 0.0% skip:98.1% L0:47.1% L1:52.9% BI: 0.0%
[libx264 @ 0000000001244ae0] 8x8 transform intra:71.6% inter:84.1%
[libx264 @ 0000000001244ae0] coded y,uvDC,uvAC intra: 17.1% 18.0% 7.8% inter: 0.1% 0.1% 0.0%
[libx264 @ 0000000001244ae0] i16 v,h,dc,p: 61% 33% 4% 2%
[libx264 @ 0000000001244ae0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 47% 9% 41% 1% 0% 1% 0% 1% 1%
[libx264 @ 0000000001244ae0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 51% 20% 5% 2% 3% 4% 4% 3% 7%
[libx264 @ 0000000001244ae0] i8c dc,h,v,p: 81% 10% 9% 1%
[libx264 @ 0000000001244ae0] Weighted P-Frames: Y:5.6% UV:5.6%
[libx264 @ 0000000001244ae0] ref P L0: 79.4% 1.1% 12.6% 6.9%
[libx264 @ 0000000001244ae0] ref B L0: 52.6% 40.8% 6.6%
[libx264 @ 0000000001244ae0] ref B L1: 84.0% 16.0%
[libx264 @ 0000000001244ae0] kb/s:40.72
出现错误是从一个片段转换到下一个片段时出现延迟。还有另一个错误，有时会发生，第一个片段播放正常，但当第二个片段开始时，播放速度非常快，并且所有其他片段似乎同时播放。
以下是我为此示例使用和创建的文件，以及原始视频和创建的清单： https://drive.google.com/open?id=0B2kwpgNH6c0AMy0zemxuUk84clU
我是 FFmpeg 的新手，也是论坛的新手，所以如果我做错了什么，请告诉我。
有人能帮助我吗？
答案1
我找到了解决这个问题的方法。
FFmpeg 有一个标志（copyts），根据文档： “不处理输入时间戳，但保留其值并尝试对其进行清理”。
这个标志解决了我在帖子中描述的问题，使得片段转换正常。
然而，分割和转码过程会导致帧的播放时间延迟（0.7 秒）。令人惊讶的是，当我们处理 .ts 文件时，此延迟会加倍，这意味着第一帧将延迟 1.4 秒才能播放。
这个问题的解决方案也是使用另一个属性（muxdelay），它设置最大解复用解码延迟。如果我们将此属性设置为 0，则 0.7 秒的延迟将不复存在。
这意味着我的命令现在看起来像这样：
拆分：
ffmpeg.exe -i $inputVideo -vcodec copy -acodec copy -f segment -muxdelay 0 -segment_list out.m3u8 out%d.ts
转码
ffmpeg -i $segmentInput -vcodec libx264 -acodec copy -s 640:480 -copyts -muxdelay 0 $outputFilename.ts
由于某种原因，分段仍然会产生非常小的延迟（我用 2 个小视频（30 秒和 2 分钟）进行了测试，延迟为 0.08-0.1 秒，我不确定为什么会发生这种情况，我现在无法解决这个问题。如果有人找到原因，请给我发消息或在这里回答（我不知道是否允许）。
无论如何，这解决了发布的问题，我希望我能有所帮助。