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FFMPEG atempo introducing phasing for multichannel mono audio tracks
27 septembre 2021, par BrainNoWerkIs this a bug, or expected behaviour ? When converting materials from PAL to NTSC I invoke atempo as follows :


-map 0:a:? -af atempo=24000/25025 ^
-c:a pcm_s24le


I use this in a windows batch file (hence the caret) as a catch-all for all files that need to be converted, not having to deal with how many audio channels might be present or in what order.


However, when my input was a broadcast MXF with 10channel mono audio (1 per stream) it introduced wild phasing between the tracks.


Merging the tracks into a single stream to be processed by atempo resulted in no phasing.


-filter_complex "[0:a:0][0:a:1][0:a:2][0:a:3][0:a:4][0:a:5][0:a:6][0:a:7][0:a:8][0:a:9] amerge=inputs=10, atempo=24000/25025[FRC]" ^
-map "[FRC]" -c:a pcm_s24le


Is this expected behaviour ? I can't see any documentation detailing the need to first use amerge before invoking atempo.


If indeed this step is necessary, is there a way to "wildcard" the amerge operation so that I don't have to manually enter all the audio channels, and then the "inputs=" ? This would allow me to make it more universal.


This is my first question on stack overflow, so please be gentle. I've come here to find so many answers to my FFMPEG questions in the past—but this seems to be an edge case I can't get much detail on.


Thanks !


EDIT :


This output using the wildcard produces phasing :


C:\Windows>ffmpeg -ss 00:05:13.0 -r 24000/1001 -i "\\bdfs11\array21\Eps101_1920x1080_20_51_DV_CC_25fps_20210622.mov" -t 00:00:22.0 -map 0:v:0 -c:v mpeg2video -profile:v 0 -level:v 2 -b:v 50000k -minrate 50000k -maxrate 50000k -pix_fmt yuv422p -vtag xd5d -force_key_frames "expr:gte(t,n_forced*1)" -streamid 0:481 -streamid 1:129 -map 0:a:? -af atempo=24000/25025 -c:a pcm_s24le "R:\2_SERIES\%~n1_25to23976_works.%Container%" -y
ffmpeg version N-94566-gddd92ba2c6 Copyright (c) 2000-2019 the FFmpeg developers
 built with gcc 9.1.1 (GCC) 20190807
 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-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt
 libavutil 56. 33.100 / 56. 33.100
 libavcodec 58. 55.100 / 58. 55.100
 libavformat 58. 30.100 / 58. 30.100
 libavdevice 58. 9.100 / 58. 9.100
 libavfilter 7. 58.100 / 7. 58.100
 libswscale 5. 6.100 / 5. 6.100
 libswresample 3. 6.100 / 3. 6.100
 libpostproc 55. 6.100 / 55. 6.100
 [mov,mp4,m4a,3gp,3g2,mj2 @ 06ea4cc0] Could not find codec parameters for stream 12 (Subtitle: none (c708 / 0x38303763), 1920x1080, 21 kb/s): unknown codec
 Consider increasing the value for the 'analyzeduration' and 'probesize' options
 Guessed Channel Layout for Input Stream #0.2 : mono
 Guessed Channel Layout for Input Stream #0.3 : mono
 Guessed Channel Layout for Input Stream #0.4 : mono
 Guessed Channel Layout for Input Stream #0.5 : mono
 Guessed Channel Layout for Input Stream #0.6 : mono
 Guessed Channel Layout for Input Stream #0.7 : mono
 Guessed Channel Layout for Input Stream #0.8 : mono
 Guessed Channel Layout for Input Stream #0.9 : mono
 Guessed Channel Layout for Input Stream #0.10 : mono
 Guessed Channel Layout for Input Stream #0.11 : mono
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '\\bdfs11\array21\Eps101_1920x1080_20_51_DV_CC_25fps_20210622.mov':
 Metadata:
 major_brand : qt
 minor_version : 537199360
 compatible_brands: qt
 creation_time : 2021-06-22T17:39:50.000000Z
 Duration: 00:59:08.16, start: 0.000000, bitrate: 217983 kb/s
 Stream #0:0(eng): Video: prores (HQ) (apch / 0x68637061), yuv422p10le(tv, bt709, progressive), 1920x1080, 206438 kb/s, SAR 1:1 DAR 16:9, 25 fps, 25 tbr, 25 tbn, 25 tbc (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Video Media Handler
 encoder : Apple ProRes 422 HQ
 timecode : 00:59:59:00
 Stream #0:1(eng): Data: none (tmcd / 0x64636D74) (default)
 Metadata:
 rotate : 0
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Time Code Media Handler
 reel_name : untitled
 timecode : 00:59:59:00
 Stream #0:2(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:3(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:4(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:5(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:6(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:7(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:8(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:9(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:10(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:11(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:12(eng): Subtitle: none (c708 / 0x38303763), 1920x1080, 21 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Closed Caption Media Handler
 Stream mapping:
 Stream #0:0 -> #0:0 (prores (native) -> mpeg2video (native))
 Stream #0:2 -> #0:1 (pcm_s24le (native) -> pcm_s24le (native))
 Stream #0:3 -> #0:2 (pcm_s24le (native) -> pcm_s24le (native))
 Stream #0:4 -> #0:3 (pcm_s24le (native) -> pcm_s24le (native))
 Stream #0:5 -> #0:4 (pcm_s24le (native) -> pcm_s24le (native))
 Stream #0:6 -> #0:5 (pcm_s24le (native) -> pcm_s24le (native))
 Stream #0:7 -> #0:6 (pcm_s24le (native) -> pcm_s24le (native))
 Stream #0:8 -> #0:7 (pcm_s24le (native) -> pcm_s24le (native))
 Stream #0:9 -> #0:8 (pcm_s24le (native) -> pcm_s24le (native))
 Stream #0:10 -> #0:9 (pcm_s24le (native) -> pcm_s24le (native))
 Stream #0:11 -> #0:10 (pcm_s24le (native) -> pcm_s24le (native))
 Press [q] to stop, [?] for help
 [mpeg2video @ 06f8aa40] Automatically choosing VBV buffer size of 746 kbyte
 Output #0, mxf, to 'R:\2_SERIES\Eps101_1920x1080_20_51_DV_CC_25fps_20210622_25to23976_works.mxf':
 Metadata:
 major_brand : qt
 minor_version : 537199360
 compatible_brands: qt
 encoder : Lavf58.30.100
 Stream #0:0(eng): Video: mpeg2video (4:2:2) (xd5d / 0x64356478), yuv422p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 50000 kb/s, 23.98 fps, 23.98 tbn, 23.98 tbc (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Video Media Handler
 timecode : 00:59:59:00
 encoder : Lavc58.55.100 mpeg2video
 Side data:
 cpb: bitrate max/min/avg: 50000000/50000000/50000000 buffer size: 6111232 vbv_delay: 18446744073709551615
 Stream #0:1(eng): Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 encoder : Lavc58.55.100 pcm_s24le
 Stream #0:2(eng): Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 encoder : Lavc58.55.100 pcm_s24le
 Stream #0:3(eng): Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 encoder : Lavc58.55.100 pcm_s24le
 Stream #0:4(eng): Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 encoder : Lavc58.55.100 pcm_s24le
 Stream #0:5(eng): Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 encoder : Lavc58.55.100 pcm_s24le
 Stream #0:6(eng): Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 encoder : Lavc58.55.100 pcm_s24le
 Stream #0:7(eng): Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 encoder : Lavc58.55.100 pcm_s24le
 Stream #0:8(eng): Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 encoder : Lavc58.55.100 pcm_s24le
 Stream #0:9(eng): Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 encoder : Lavc58.55.100 pcm_s24le
 Stream #0:10(eng): Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 encoder : Lavc58.55.100 pcm_s24le
 frame= 527 fps= 52 q=2.0 Lsize= 166106kB time=00:00:22.00 bitrate=61851.7kbits/s speed=2.19x
 video:133971kB audio:30938kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.726204%


This is the output that produces no phasing


C:\Windows>ffmpeg -ss 00:05:13.0 -r 24000/1001 -i "\\bdfs11\array21\Eps101_1920x1080_20_51_DV_CC_25fps_20210622.mov" -t 00:00:22.0 -map 0:v:0 -c:v mpeg2video -profile:v 0 -level:v 2 -b:v 50000k -minrate 50000k -maxrate 50000k -pix_fmt yuv422p -vtag xd5d -force_key_frames "expr:gte(t,n_forced*1)" -streamid 0:481 -streamid 1:129 -filter_complex "[0:a:0][0:a:1][0:a:2][0:a:3][0:a:4][0:a:5][0:a:6][0:a:7][0:a:8][0:a:9] amerge=inputs=10, atempo=24000/25025[FRC]" -map "[FRC]" -c:a pcm_s24le "R:\2_SERIES\Eps101_1920x1080_20_51_DV_CC_25fps_20210622_25to23976_works.mxf" -y
ffmpeg version N-94566-gddd92ba2c6 Copyright (c) 2000-2019 the FFmpeg developers
 built with gcc 9.1.1 (GCC) 20190807
 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-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt
 libavutil 56. 33.100 / 56. 33.100
 libavcodec 58. 55.100 / 58. 55.100
 libavformat 58. 30.100 / 58. 30.100
 libavdevice 58. 9.100 / 58. 9.100
 libavfilter 7. 58.100 / 7. 58.100
 libswscale 5. 6.100 / 5. 6.100
 libswresample 3. 6.100 / 3. 6.100
 libpostproc 55. 6.100 / 55. 6.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 064f5580] Could not find codec parameters for stream 12 (Subtitle: none (c708 / 0x38303763), 1920x1080, 21 kb/s): unknown codec
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Guessed Channel Layout for Input Stream #0.2 : mono
Guessed Channel Layout for Input Stream #0.3 : mono
Guessed Channel Layout for Input Stream #0.4 : mono
Guessed Channel Layout for Input Stream #0.5 : mono
Guessed Channel Layout for Input Stream #0.6 : mono
Guessed Channel Layout for Input Stream #0.7 : mono
Guessed Channel Layout for Input Stream #0.8 : mono
Guessed Channel Layout for Input Stream #0.9 : mono
Guessed Channel Layout for Input Stream #0.10 : mono
Guessed Channel Layout for Input Stream #0.11 : mono
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '\\bdfs11\array21\Eps101_1920x1080_20_51_DV_CC_25fps_20210622.mov':
 Metadata:
 major_brand : qt
 minor_version : 537199360
 compatible_brands: qt
 creation_time : 2021-06-22T17:39:50.000000Z
 Duration: 00:59:08.16, start: 0.000000, bitrate: 217983 kb/s
 Stream #0:0(eng): Video: prores (HQ) (apch / 0x68637061), yuv422p10le(tv, bt709, progressive), 1920x1080, 206438 kb/s, SAR 1:1 DAR 16:9, 25 fps, 25 tbr, 25 tbn, 25 tbc (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Video Media Handler
 encoder : Apple ProRes 422 HQ
 timecode : 00:59:59:00
 Stream #0:1(eng): Data: none (tmcd / 0x64636D74) (default)
 Metadata:
 rotate : 0
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Time Code Media Handler
 reel_name : untitled
 timecode : 00:59:59:00
 Stream #0:2(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:3(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:4(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:5(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:6(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:7(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:8(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:9(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:10(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:11(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Sound Media Handler
 Stream #0:12(eng): Subtitle: none (c708 / 0x38303763), 1920x1080, 21 kb/s (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Closed Caption Media Handler
Stream mapping:
 Stream #0:2 (pcm_s24le) -> amerge:in0 (graph 0)
 Stream #0:3 (pcm_s24le) -> amerge:in1 (graph 0)
 Stream #0:4 (pcm_s24le) -> amerge:in2 (graph 0)
 Stream #0:5 (pcm_s24le) -> amerge:in3 (graph 0)
 Stream #0:6 (pcm_s24le) -> amerge:in4 (graph 0)
 Stream #0:7 (pcm_s24le) -> amerge:in5 (graph 0)
 Stream #0:8 (pcm_s24le) -> amerge:in6 (graph 0)
 Stream #0:9 (pcm_s24le) -> amerge:in7 (graph 0)
 Stream #0:10 (pcm_s24le) -> amerge:in8 (graph 0)
 Stream #0:11 (pcm_s24le) -> amerge:in9 (graph 0)
 Stream #0:0 -> #0:0 (prores (native) -> mpeg2video (native))
 atempo (graph 0) -> Stream #0:1 (pcm_s24le)
Press [q] to stop, [?] for help
[Parsed_amerge_0 @ 06e18dc0] No channel layout for input 1
[Parsed_amerge_0 @ 06e18dc0] Input channel layouts overlap: output layout will be determined by the number of distinct input channels
[mpeg2video @ 06dea000] Automatically choosing VBV buffer size of 746 kbyte
Output #0, mxf, to 'R:\2_SERIES\Eps101_1920x1080_20_51_DV_CC_25fps_20210622_25to23976_works.mxf':
 Metadata:
 major_brand : qt
 minor_version : 537199360
 compatible_brands: qt
 encoder : Lavf58.30.100
 Stream #0:0(eng): Video: mpeg2video (4:2:2) (xd5d / 0x64356478), yuv422p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 50000 kb/s, 23.98 fps, 23.98 tbn, 23.98 tbc (default)
 Metadata:
 creation_time : 2021-06-22T17:39:50.000000Z
 handler_name : Apple Video Media Handler
 timecode : 00:59:59:00
 encoder : Lavc58.55.100 mpeg2video
 Side data:
 cpb: bitrate max/min/avg: 50000000/50000000/50000000 buffer size: 6111232 vbv_delay: 18446744073709551615
 Stream #0:1: Audio: pcm_s24le, 48000 Hz, 10 channels (FL+FR+FC+LFE+BL+BR+FLC+FRC+BC+SL), s32, 11520 kb/s (default)
 Metadata:
 encoder : Lavc58.55.100 pcm_s24le
frame= 527 fps= 61 q=2.0 Lsize= 165571kB time=00:00:22.00 bitrate=61652.6kbits/s speed=2.56x
video:133971kB audio:30938kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.402084%


Let me know if you need more detail than what I've provided.


Tangential questions related to this job and potentially not worth their own thread, even though I've looked extensively and not found the answers (happy to post them individually if that's necessary) :


- 

-
I can't seem to split any portion of the filter_complex above with a caret (^) within a windows batch file (no number of spaces before or after resolve this issue). It breaks the chain and the filter graphs complain of no input.


-
Is FFMBC still the only way to include broadcast closed captioning ? This functionality doesn't exist within FFMPEG ?








-
-
record mediasoup RTP stream using FFmpeg for Firefox
30 juillet 2024, par Hadi AghandehI am trying to record WebRTC stream using mediasoup. I could record successfully on chrome and safari 13/14/15. However on Firefox the does not work.


Client side code is a vue js component which gets rtp-compabilities using socket.io and create producers after the server creates the transports. This works good on chrome and safari.


const { connect , createLocalTracks } = require('twilio-video');
const SocketClient = require("socket.io-client");
const SocketPromise = require("socket.io-promise").default;
const MediasoupClient = require("mediasoup-client");

export default {
 data() {
 return {
 errors: [],
 isReady: false,
 isRecording: false,
 loading: false,
 sapio: {
 token: null,
 connectionId: 0
 },
 server: {
 host: 'https://rtc.test',
 ws: '/server',
 socket: null,
 },
 peer: {},
 }
 },
 mounted() {
 this.init();
 },
 methods: {
 async init() {
 await this.startCamera();

 if (this.takeId) {
 await this.recordBySapioServer();
 }
 },
 startCamera() {
 return new Promise( (resolve, reject) => {
 if (window.videoMediaStreamObject) {
 this.setVideoElementStream(window.videoMediaStreamObject);
 resolve();
 } else {
 // Get user media as required
 try {
 this.localeStream = navigator.mediaDevices.getUserMedia({
 audio: true,
 video: true,
 }).then((stream) => {
 this.setVideoElementStream(stream);
 resolve();
 })
 } catch (err) {
 console.error(err);
 reject();
 }
 }
 })
 },
 setVideoElementStream(stream) {
 this.localStream = stream;
 this.$refs.video.srcObject = stream;
 this.$refs.video.muted = true;
 this.$refs.video.play().then((video) => {
 this.isStreaming = true;
 this.height = this.$refs.video.videoHeight;
 this.width = this.$refs.video.videoWidth;
 });
 },
 // first thing we need is connecting to websocket
 connectToSocket() {
 const serverUrl = this.server.host;
 console.log("Connect with sapio rtc server:", serverUrl);

 const socket = SocketClient(serverUrl, {
 path: this.server.ws,
 transports: ["websocket"],
 });
 this.socket = socket;

 socket.on("connect", () => {
 console.log("WebSocket connected");
 // we ask for rtp-capabilities from server to send to us
 socket.emit('send-rtp-capabilities');
 });

 socket.on("error", (err) => {
 this.loading = true;
 console.error("WebSocket error:", err);
 });

 socket.on("router-rtp-capabilities", async (msg) => {
 const { routerRtpCapabilities, sessionId, externalId } = msg;
 console.log('[rtpCapabilities:%o]', routerRtpCapabilities);
 this.routerRtpCapabilities = routerRtpCapabilities;

 try {
 const device = new MediasoupClient.Device();
 // Load the mediasoup device with the router rtp capabilities gotten from the server
 await device.load({ routerRtpCapabilities });

 this.peer.sessionId = sessionId;
 this.peer.externalId = externalId;
 this.peer.device = device;

 this.createTransport();
 } catch (error) {
 console.error('failed to init device [error:%o]', error);
 socket.disconnect();
 }
 });

 socket.on("create-transport", async (msg) => {
 console.log('handleCreateTransportRequest() [data:%o]', msg);

 try {
 // Create the local mediasoup send transport
 this.peer.sendTransport = await this.peer.device.createSendTransport(msg);
 console.log('send transport created [id:%s]', this.peer.sendTransport.id);

 // Set the transport listeners and get the users media stream
 this.handleSendTransportListeners();
 this.setTracks();
 this.loading = false;
 } catch (error) {
 console.error('failed to create transport [error:%o]', error);
 socket.disconnect();
 }
 });

 socket.on("connect-transport", async (msg) => {
 console.log('handleTransportConnectRequest()');
 try {
 const action = this.connectTransport;

 if (!action) {
 throw new Error('transport-connect action was not found');
 }

 await action(msg);
 } catch (error) {
 console.error('ailed [error:%o]', error);
 }
 });

 socket.on("produce", async (msg) => {
 console.log('handleProduceRequest()');
 try {
 if (!this.produce) {
 throw new Error('produce action was not found');
 }
 await this.produce(msg);
 } catch (error) {
 console.error('failed [error:%o]', error);
 }
 });

 socket.on("recording", async (msg) => {
 this.isRecording = true;
 });

 socket.on("recording-error", async (msg) => {
 this.isRecording = false;
 console.error(msg);
 });

 socket.on("recording-closed", async (msg) => {
 this.isRecording = false;
 console.warn(msg)
 });

 },
 createTransport() {
 console.log('createTransport()');

 if (!this.peer || !this.peer.device.loaded) {
 throw new Error('Peer or device is not initialized');
 }

 // First we must create the mediasoup transport on the server side
 this.socket.emit('create-transport',{
 sessionId: this.peer.sessionId
 });
 },
 handleSendTransportListeners() {
 this.peer.sendTransport.on('connect', this.handleTransportConnectEvent);
 this.peer.sendTransport.on('produce', this.handleTransportProduceEvent);
 this.peer.sendTransport.on('connectionstatechange', connectionState => {
 console.log('send transport connection state change [state:%s]', connectionState);
 });
 },
 handleTransportConnectEvent({ dtlsParameters }, callback, errback) {
 console.log('handleTransportConnectEvent()');
 try {
 this.connectTransport = (msg) => {
 console.log('connect-transport action');
 callback();
 this.connectTransport = null;
 };

 this.socket.emit('connect-transport',{
 sessionId: this.peer.sessionId,
 transportId: this.peer.sendTransport.id,
 dtlsParameters
 });

 } catch (error) {
 console.error('handleTransportConnectEvent() failed [error:%o]', error);
 errback(error);
 }
 },
 handleTransportProduceEvent({ kind, rtpParameters }, callback, errback) {
 console.log('handleTransportProduceEvent()');
 try {
 this.produce = jsonMessage => {
 console.log('handleTransportProduceEvent callback [data:%o]', jsonMessage);
 callback({ id: jsonMessage.id });
 this.produce = null;
 };

 this.socket.emit('produce', {
 sessionId: this.peer.sessionId,
 transportId: this.peer.sendTransport.id,
 kind,
 rtpParameters
 });
 } catch (error) {
 console.error('handleTransportProduceEvent() failed [error:%o]', error);
 errback(error);
 }
 },
 async recordBySapioServer() {
 this.loading = true;
 this.connectToSocket();
 },
 async setTracks() {
 // Start mediasoup-client's WebRTC producers
 const audioTrack = this.localStream.getAudioTracks()[0];
 this.peer.audioProducer = await this.peer.sendTransport.produce({
 track: audioTrack,
 codecOptions :
 {
 opusStereo : 1,
 opusDtx : 1
 }
 });


 let encodings;
 let codec;
 const codecOptions = {videoGoogleStartBitrate : 1000};

 codec = this.peer.device.rtpCapabilities.codecs.find((c) => c.kind.toLowerCase() === 'video');
 if (codec.mimeType.toLowerCase() === 'video/vp9') {
 encodings = { scalabilityMode: 'S3T3_KEY' };
 } else {
 encodings = [
 { scaleResolutionDownBy: 4, maxBitrate: 500000 },
 { scaleResolutionDownBy: 2, maxBitrate: 1000000 },
 { scaleResolutionDownBy: 1, maxBitrate: 5000000 }
 ];
 }
 const videoTrack = this.localStream.getVideoTracks()[0];
 this.peer.videoProducer =await this.peer.sendTransport.produce({
 track: videoTrack,
 encodings,
 codecOptions,
 codec
 });

 },
 startRecording() {
 this.Q.answer.recordingId = this.peer.externalId;
 this.socket.emit("start-record", {
 sessionId: this.peer.sessionId
 });
 },
 stopRecording() {
 this.socket.emit("stop-record" , {
 sessionId: this.peer.sessionId
 });
 },
 },

}





console.log of my ffmpeg process :


// sdp string
[sdpString:v=0
 o=- 0 0 IN IP4 127.0.0.1
 s=FFmpeg
 c=IN IP4 127.0.0.1
 t=0 0
 m=video 25549 RTP/AVP 101 
 a=rtpmap:101 VP8/90000
 a=sendonly
 m=audio 26934 RTP/AVP 100 
 a=rtpmap:100 opus/48000/2
 a=sendonly
 ]

// ffmpeg args
commandArgs:[
 '-loglevel',
 'debug',
 '-protocol_whitelist',
 'pipe,udp,rtp',
 '-fflags',
 '+genpts',
 '-f',
 'sdp',
 '-i',
 'pipe:0',
 '-map',
 '0:v:0',
 '-c:v',
 'copy',
 '-map',
 '0:a:0',
 '-strict',
 '-2',
 '-c:a',
 'copy',
 '-f',
 'webm',
 '-flags',
 '+global_header',
 '-y',
 'storage/recordings/26e63cb3-4f81-499e-941a-c0bb7f7f52ce.webm',
 [length]: 26
]
// ffmpeg log
ffmpeg::process::data [data:'ffmpeg version n4.4']
ffmpeg::process::data [data:' Copyright (c) 2000-2021 the FFmpeg developers']
ffmpeg::process::data [data:'\n']
ffmpeg::process::data [data:' built with gcc 11.1.0 (GCC)\n']
ffmpeg::process::data [data:' configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmfx --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librav1e --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-libzimg --enable-nvdec --enable-nvenc --enable-shared --enable-version3\n']
ffmpeg::process::data [data:' libavutil 56. 70.100 / 56. 70.100\n' +
 ' libavcodec 58.134.100 / 58.134.100\n' +
 ' libavformat 58. 76.100 / 58. 76.100\n' +
 ' libavdevice 58. 13.100 / 58. 13.100\n' +
 ' libavfilter 7.110.100 / 7.110.100\n' +
 ' libswscale 5. 9.100 / 5. 9.100\n' +
 ' libswresample 3. 9.100 / 3. 9.100\n' +
 ' libpostproc 55. 9.100 / 55. 9.100\n' +
 'Splitting the commandline.\n' +
 "Reading option '-loglevel' ... matched as option 'loglevel' (set logging level) with argument 'debug'.\n" +
 "Reading option '-protocol_whitelist' ..."]
ffmpeg::process::data [data:" matched as AVOption 'protocol_whitelist' with argument 'pipe,udp,rtp'.\n" +
 "Reading option '-fflags' ..."]
ffmpeg::process::data [data:" matched as AVOption 'fflags' with argument '+genpts'.\n" +
 "Reading option '-f' ... matched as option 'f' (force format) with argument 'sdp'.\n" +
 "Reading option '-i' ... matched as input url with argument 'pipe:0'.\n" +
 "Reading option '-map' ... matched as option 'map' (set input stream mapping) with argument '0:v:0'.\n" +
 "Reading option '-c:v' ... matched as option 'c' (codec name) with argument 'copy'.\n" +
 "Reading option '-map' ... matched as option 'map' (set input stream mapping) with argument '0:a:0'.\n" +
 "Reading option '-strict' ...Routing option strict to both codec and muxer layer\n" +
 " matched as AVOption 'strict' with argument '-2'.\n" +
 "Reading option '-c:a' ... matched as option 'c' (codec name) with argument 'copy'.\n" +
 "Reading option '-f' ... matched as option 'f' (force format) with argument 'webm'.\n" +
 "Reading option '-flags' ... matched as AVOption 'flags' with argument '+global_header'.\n" +
 "Reading option '-y' ... matched as option 'y' (overwrite output files) with argument '1'.\n" +
 "Reading option 'storage/recordings/26e63cb3-4f81-499e-941a-c0bb7f7f52ce.webm' ... matched as output url.\n" +
 'Finished splitting the commandline.\n' +
 'Parsing a group of options: global .\n' +
 'Applying option loglevel (set logging level) with argument debug.\n' +
 'Applying option y (overwrite output files) with argument 1.\n' +
 'Successfully parsed a group of options.\n' +
 'Parsing a group of options: input url pipe:0.\n' +
 'Applying option f (force format) with argument sdp.\n' +
 'Successfully parsed a group of options.\n' +
 'Opening an input file: pipe:0.\n' +
 "[sdp @ 0x55604dc58400] Opening 'pipe:0' for reading\n" +
 '[sdp @ 0x55604dc58400] video codec set to: vp8\n' +
 '[sdp @ 0x55604dc58400] audio codec set to: opus\n' +
 '[sdp @ 0x55604dc58400] audio samplerate set to: 48000\n' +
 '[sdp @ 0x55604dc58400] audio channels set to: 2\n' +
 '[udp @ 0x55604dc6c500] end receive buffer size reported is 425984\n' +
 '[udp @ 0x55604dc6c7c0] end receive buffer size reported is 425984\n' +
 '[sdp @ 0x55604dc58400] setting jitter buffer size to 500\n' +
 '[udp @ 0x55604dc6d900] end receive buffer size reported is 425984\n' +
 '[udp @ 0x55604dc6d2c0] end receive buffer size reported is 425984\n' +
 '[sdp @ 0x55604dc58400] setting jitter buffer size to 500\n']
ffmpeg::process::data [data:'[sdp @ 0x55604dc58400] Before avformat_find_stream_info() pos: 210 bytes read:210 seeks:0 nb_streams:2\n']
 **mediasoup:Consumer resume() +1s**
 **mediasoup:Channel request() [method:consumer.resume, id:12] +1s**
 **mediasoup:Channel request succeeded [method:consumer.resume, id:12] +0ms**
 **mediasoup:Consumer resume() +1ms**
 **mediasoup:Channel request() [method:consumer.resume, id:13] +0ms**
 **mediasoup:Channel request succeeded [method:consumer.resume, id:13] +0ms**
ffmpeg::process::data [data:'[sdp @ 0x55604dc58400] Could not find codec parameters for stream 0 (Video: vp8, 1 reference frame, yuv420p): unspecified size\n' +
 "Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options\n"]
ffmpeg::process::data [data:'[sdp @ 0x55604dc58400] After avformat_find_stream_info() pos: 210 bytes read:210 seeks:0 frames:0\n' +
 "Input #0, sdp, from 'pipe:0':\n" +
 ' Metadata:\n' +
 ' title : FFmpeg\n' +
 ' Duration: N/A, bitrate: N/A\n' +
 ' Stream #0:0, 0, 1/90000: Video: vp8, 1 reference frame, yuv420p, 90k tbr, 90k tbn, 90k tbc\n' +
 ' Stream #0:1, 0, 1/48000: Audio: opus, 48000 Hz, stereo, fltp\n' +
 'Successfully opened the file.\n' +
 'Parsing a group of options: output url storage/recordings/26e63cb3-4f81-499e-941a-c0bb7f7f52ce.webm.\n' +
 'Applying option map (set input stream mapping) with argument 0:v:0.\n' +
 'Applying option c:v (codec name) with argument copy.\n' +
 'Applying option map (set input stream mapping) with argument 0:a:0.\n' +
 'Applying option c:a (codec name) with argument copy.\n' +
 'Applying option f (force format) with argument webm.\n' +
 'Successfully parsed a group of options.\n' +
 'Opening an output file: storage/recordings/26e63cb3-4f81-499e-941a-c0bb7f7f52ce.webm.\n' +
 "[file @ 0x55604dce5bc0] Setting default whitelist 'file,crypto,data'\n"]
ffmpeg::process::data [data:'Successfully opened the file.\n' +
 '[webm @ 0x55604dce0fc0] dimensions not set\n' +
 'Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument\n' +
 'Error initializing output stream 0:1 -- \n' +
 'Stream mapping:\n' +
 ' Stream #0:0 -> #0:0 (copy)\n' +
 ' Stream #0:1 -> #0:1 (copy)\n' +
 ' Last message repeated 1 times\n' +
 '[AVIOContext @ 0x55604dc6dcc0] Statistics: 0 seeks, 0 writeouts\n' +
 '[AVIOContext @ 0x55604dc69380] Statistics: 210 bytes read, 0 seeks\n']
ffmpeg::process::close



FFmpeg says
dimensions not setandCould not write header for output filewhen I use Firefox. This might be enough for understanding the problem, but if you need more information you can read how server side is performing.
Server-Side in summary can be something like this :
lets say we initialized worker and router at run time using following functions.

// Start the mediasoup workers
module.exports.initializeWorkers = async () => {
 const { logLevel, logTags, rtcMinPort, rtcMaxPort } = config.worker;

 console.log('initializeWorkers() creating %d mediasoup workers', config.numWorkers);

 for (let i = 0; i < config.numWorkers; ++i) {
 const worker = await mediasoup.createWorker({
 logLevel, logTags, rtcMinPort, rtcMaxPort
 });

 worker.once('died', () => {
 console.error('worker::died worker has died exiting in 2 seconds... [pid:%d]', worker.pid);
 setTimeout(() => process.exit(1), 2000);
 });

 workers.push(worker);
 }
};


module.exports.createRouter = async () => {
 const worker = getNextWorker();

 console.log('createRouter() creating new router [worker.pid:%d]', worker.pid);

 console.log(`config.router.mediaCodecs:${JSON.stringify(config.router.mediaCodecs)}`)

 return await worker.createRouter({ mediaCodecs: config.router.mediaCodecs });
};


We pass
router.rtpCompatibilitiesto the client. clients get thertpCompatibilitiesand create a device and loads it. after that a transport must be created at server side.

const handleCreateTransportRequest = async (jsonMessage) => {

 const transport = await createTransport('webRtc', router);

 var peer;
 try {peer = peers.get(jsonMessage.sessionId);}
 catch{console.log('peer not found')}
 
 peer.addTransport(transport);

 peer.socket.emit('create-transport',{
 id: transport.id,
 iceParameters: transport.iceParameters,
 iceCandidates: transport.iceCandidates,
 dtlsParameters: transport.dtlsParameters
 });
};


Then after the client side also created the transport we listen to connect event an at the time of event, we request the server to create connection.


const handleTransportConnectRequest = async (jsonMessage) => {
 var peer;
 try {peer = peers.get(jsonMessage.sessionId);}
 catch{console.log('peer not found')}

 if (!peer) {
 throw new Error(`Peer with id ${jsonMessage.sessionId} was not found`);
 }

 const transport = peer.getTransport(jsonMessage.transportId);

 if (!transport) {
 throw new Error(`Transport with id ${jsonMessage.transportId} was not found`);
 }

 await transport.connect({ dtlsParameters: jsonMessage.dtlsParameters });
 console.log('handleTransportConnectRequest() transport connected');
 peer.socket.emit('connect-transport');
};


Similar thing happen on produce event.


const handleProduceRequest = async (jsonMessage) => {
 console.log('handleProduceRequest [data:%o]', jsonMessage);

 var peer;
 try {peer = peers.get(jsonMessage.sessionId);}
 catch{console.log('peer not found')}

 if (!peer) {
 throw new Error(`Peer with id ${jsonMessage.sessionId} was not found`);
 }

 const transport = peer.getTransport(jsonMessage.transportId);

 if (!transport) {
 throw new Error(`Transport with id ${jsonMessage.transportId} was not found`);
 }

 const producer = await transport.produce({
 kind: jsonMessage.kind,
 rtpParameters: jsonMessage.rtpParameters
 });

 peer.addProducer(producer);

 console.log('handleProducerRequest() new producer added [id:%s, kind:%s]', producer.id, producer.kind);

 peer.socket.emit('produce',{
 id: producer.id,
 kind: producer.kind
 });
};


For Recording, first I create plain transports for audio and video producers.


const rtpTransport = router.createPlainTransport(config.plainRtpTransport);


then rtp transport must be connected to ports :


await rtpTransport.connect({
 ip: '127.0.0.1',
 port: remoteRtpPort,
 rtcpPort: remoteRtcpPort
 });


Then the consumer must also be created.


const rtpConsumer = await rtpTransport.consume({
 producerId: producer.id,
 rtpCapabilities,
 paused: true
 });


After that we can start recording using following code :


this._rtpParameters = args;
 this._process = undefined;
 this._observer = new EventEmitter();
 this._peer = args.peer;

 this._sdpString = createSdpText(this._rtpParameters);
 this._sdpStream = convertStringToStream(this._sdpString);
 // create dir
 const dir = process.env.REOCRDING_PATH ?? 'storage/recordings';
 if (!fs.existsSync(dir)) shelljs.mkdir('-p', dir);
 
 this._extension = 'webm';
 // create file path
 this._path = `${dir}/${args.peer.sessionId}.${this._extension}`
 let loop = 0;
 while(fs.existsSync(this._path)) {
 this._path = `${dir}/${args.peer.sessionId}-${++loop}.${this._extension}`
 }

this._recordingnModel = await Recording.findOne({sessionIds: { $in: [this._peer.sessionId] }})
 this._recordingnModel.files.push(this._path);
 this._recordingnModel.save();

let proc = ffmpeg(this._sdpStream)
 .inputOptions([
 '-protocol_whitelist','pipe,udp,rtp',
 '-f','sdp',
 ])
 .format(this._extension)
 .output(this._path)
 .size('720x?')
 .on('start', ()=>{
 this._peer.socket.emit('recording');
 })
 .on('end', ()=>{
 let path = this._path.replace('storage/recordings/', '');
 this._peer.socket.emit('recording-closed', {
 url: `${process.env.APP_URL}/recording/file/${path}`
 });
 });

 proc.run();
 this._process = proc;
 }



-
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