No Video track after webm -> h264 (mp4) batch conversion

[fontanm]

Hello VLCer

I am using VLC (currently on windows 10 machine) quite successfully for converting webm videos into mp4 (h264/mp4a) files in order to save storage space. (I use it for archiving my meetings with clients.)

Recently, however, I have realized that sometimes conversion ends with mp4 file that is missing video track (or the track is empty). I have not received any error message while processing and I am unable to reproduce it when trying this again on the same video (problem is that my conversion runs automatically and deletes source video after conversion so I miss video track completely if I do not see the problem soon enough)

command line argument that i run on each webm file is as follows:

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"-I dummy -vvv `"$($inputFile.FullName)`" --sout=#transcode{vcodec=`"h264`",acodec=`"mp4a`",ab=`"128`",`"channels=2`",samlperate`"44100`"}:file{dst=`"$outputFileName`"} vlc://quit"

is there anything I may add/check/adjust in order to avoid this problem? or have you ever experienced anything like that?

Thanks a lot

[fontanm]

I am still struggling with this issue but now I have returned to it and found that in some cases VLC won't write VideHandler part into the output. It seems that the video data are in the converted file but no player is able to use them as video handler information is missing completely.

see output from the ffprobe:

Correct File:

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Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '.\c.mp4': Metadata: major_brand : isom minor_version : 0 compatible_brands: mp41avc1 creation_time : 2021-01-29T07:35:47.000000Z playback_requirements: QuickTime 6.0 or greater playback_requirements-eng: QuickTime 6.0 or greater encoder : vlc 3.0.11 stream output encoder-eng : vlc 3.0.11 stream output Duration: 00:16:44.55, start: 0.000000, bitrate: 377 kb/s Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt470bg/unknown/unknown), 1366x768 [SAR 1:1 DAR 683:384], 243 kb/s, 9.90 fps, 60 tbr, 1000k tbn, 50 tbc (default) Metadata: creation_time : 2021-01-29T07:35:47.000000Z handler_name : VideoHandler Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 127 kb/s (default) Metadata: creation_time : 2021-01-29T07:35:47.000000Z handler_name : SoundHandler 3.32 A-V: 0.004 fd= 0 aq= 146KB vq= 237KB sq= 0B f=0/0

Corrupted File:

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Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '.\a.mp4':sq= 0B f=0/0 Metadata: major_brand : isom minor_version : 0 compatible_brands: mp41avc1 creation_time : 2021-02-02T10:54:50.000000Z playback_requirements: QuickTime 6.0 or greater playback_requirements-eng: QuickTime 6.0 or greater encoder : vlc 3.0.12 stream output encoder-eng : vlc 3.0.12 stream output Duration: 00:44:31.87, start: 0.000000, bitrate: 131 kb/s Stream #0:0(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 127 kb/s (default) Metadata: creation_time : 2021-02-02T10:54:50.000000Z handler_name : SoundHandler 10.68 M-A: -0.000 fd= 0 aq= 20KB vq= 0KB sq= 0B f=0/0

both files have been converted using exactly the same conversion command (see my first post)

[Lotesdelere]

There are other reports about conversion issues:
https://forum.videolan.org/viewtopic.ph ... 89#p508489

Try with a nightly build:
https://nightlies.videolan.org

Or use a dedicated video tool such as AviDemux:
http://avidemux.sourceforge.net