我使用avcodec（c ++）api解码视频文件帧并处理它们。我注意到解码的帧数小于预期的\实际帧数。差异是16帧。 虽然x帧是用ffmpeg解码的，但VirtualDub说同一个文件有x + 16帧。 使用ffprobe，我看到该文件包含x帧：
$ ffprobe -v error -count_frames -select_streams v:0 -show_entries stream=nb_read_frames -of default=nokey=1:noprint_wrappers=1 inputFile.avi
10875
此外，当我尝试使用ffmpeg实用程序提取x + 1帧时，我遇到了失败：
$ ffmpeg -i inputFile.avi -vf "select=eq(n\,10875)" -vframes 1 outPic.jpg
ffmpeg version N-80801-gc0cb53c Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 5.4.0 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --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. 27.100 / 55. 27.100
libavcodec 57. 48.101 / 57. 48.101
libavformat 57. 40.101 / 57. 40.101
libavdevice 57. 0.102 / 57. 0.102
libavfilter 6. 46.102 / 6. 46.102
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 1.100 / 2. 1.100
libpostproc 54. 0.100 / 54. 0.100
Input #0, avi, from 'inputFile.avi':
Metadata:
comment : Recorder-v2
encoder : Lavf57.40.101
Duration: 00:18:09.10, start: 0.000000, bitrate: 3421 kb/s
Stream #0:0: Video: mpeg4 (Simple Profile) (xvid / 0x64697678), yuv420p, 1280x960 [SAR 1:1 DAR 4:3], 3420 kb/s, 10 fps, 10 tbr, 10 tbn, 10 tbc
[swscaler @ 00000000021100a0] deprecated pixel format used, make sure you did set range correctly
[image2 @ 0000000001f10540] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
Output #0, image2, to 'outPic.jpg':
Metadata:
comment : Recorder-v2
encoder : Lavf57.40.101
Stream #0:0: Video: mjpeg, yuvj420p(pc), 1280x960 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 10 fps, 10 tbn, 10 tbc
Metadata:
encoder : Lavc57.48.101 mjpeg
Side data:
cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
Stream mapping:
Stream #0:0 -> #0:0 (mpeg4 (native) -> mjpeg (native))
Press [q] to stop, [?] for help
frame= 0 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A speed= 0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)
有趣和奇怪的部分是按照序列生成x + 16个文件（相同的帧编号VirutalDub声称）保存这部电影的所有帧：
$ ffmpeg -i inputFile.avi "frames/out-%03d.jpg"
ffmpeg version N-80801-gc0cb53c Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 5.4.0 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --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. 27.100 / 55. 27.100
libavcodec 57. 48.101 / 57. 48.101
libavformat 57. 40.101 / 57. 40.101
libavdevice 57. 0.102 / 57. 0.102
libavfilter 6. 46.102 / 6. 46.102
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 1.100 / 2. 1.100
libpostproc 54. 0.100 / 54. 0.100
Input #0, avi, from 'inputFile.avi':
Metadata:
comment : Recorder-v2
encoder : Lavf57.40.101
Duration: 00:18:09.10, start: 0.000000, bitrate: 3421 kb/s
Stream #0:0: Video: mpeg4 (Simple Profile) (xvid / 0x64697678), yuv420p, 1280x960 [SAR 1:1 DAR 4:3], 3420 kb/s, 10 fps, 10 tbr, 10 tbn, 10 tbc
[swscaler @ 00000000020600a0] deprecated pixel format used, make sure you did set range correctly
[image2 @ 0000000001d20540] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
Output #0, image2, to 'frames/out-%03d.jpg':
Metadata:
comment : Recorder-v2
encoder : Lavf57.40.101
Stream #0:0: Video: mjpeg, yuvj420p(pc), 1280x960 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 10 fps, 10 tbn, 10 tbc
Metadata:
encoder : Lavc57.48.101 mjpeg
Side data:
cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
Stream mapping:
Stream #0:0 -> #0:0 (mpeg4 (native) -> mjpeg (native))
Press [q] to stop, [?] for help
frame=10891 fps=120 q=24.8 Lsize=N/A time=00:18:09.10 bitrate=N/A dup=16 drop=0 speed= 12x
video:384325kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
计算的文件数/帧数：
$ ls -l frames/* | wc -l
10891
我在这里很丢失。任何线索为什么avcodec解码x帧而不是x + 16？ ffmpeg错过了帧吗？ VirtualDub可能重复（16）帧吗？
由于
答案 0 :(得分：0)
可能的原因是＆＃34;丢帧＆＃34;，您可以使用VirtualDub热键＆＃34; Go - ＆gt;进行检查。下一帧下架＆＃34;。 FFmpeg不会将它们视为独立帧，但您可以注意到时间码中的跳跃。
答案 1 :(得分：0)
或者您可能会忘记在编写框架之前重新调整时间戳记：
av_packet_rescale_ts(&pkt, codec_context->time_base, stream->time_base);