VLC does not plays sound on some part of webex recordings

VLC does not play some part of webex recordings converted to MP4. Other media players plays it normal like windows media player. its not full part of voice; just some small partions within video. like voice goes on 01:59 and comes again 02:14 goes for a while normal again and happens same thing. wanted to add sample file but its 12.24 MiB and 10MiB allowed.

We need the sample. Try WeTransfer

https://we.tl/t-ByBQGBGEDY

you may download with the provided link. example voice goes on 01:59 and comes again 02:14 but not happens in Windows Media Player

I have the same problem on other videos downloaded from Webex. I can provide such other videos, but they are significantly larger than @tansutekin's sample.

I can reproduce the described behavior on multiple setups:

• Windows 10, VLC 3.0.11
• Windows 10, VLC 3.0.16
• Ubuntu 20.04, VLC 3.0.9.2
• Manjaro, VLC 3.0.17.4

Audio is fine on other players (Windows Media Player, mpv, GNOME Videos, MPC-HC).

Oddly enough if I seek ahead far enough, audio will kick in, and if i seek back to the beginning it will be playing fine. But yeah can definitely confirm that it's more of a struggle to get audio playback working for this file in VLC (git HEAD in my case) than other players (mpv, ffplay and totem all play from the start without issue).

AFAICT adding --demux avformat and/or --codec avcodec doesn't seem to help either.

N.B. --no-video did lead to normal audio playback.

That IS a weird bug.

Due to real ******** up interleaving there's large chunks of audio delayed. Meanwhile, the demux can't generate a PCR while video is still playing. When audio resumes and pcr is sent, everything is late. No surprise avformat interacts the same way with the core

I can confirm that i'm also affected by this bug, along with many other students from my university, that uses Cisco WebEX. At the moment of audio loss no message is given, but when audio is recovered (after a some seconds, typically) the messages board shows:

main debug: auto hiding mouse cursor
mp4 warning: mdat had still 255534 bytes unparsed as samples
main warning: buffer too late (-11069000 us): dropped
main warning: buffer too late (-11037000 us): dropped
main warning: buffer too late (-11005000 us): dropped
[omissis]
main warning: buffer too late (-146000 us): dropped
main warning: buffer too late (-114000 us): dropped
main warning: buffer too late (-83000 us): dropped
main debug: playback too late (50999): flushing buffers
mmdevice debug: state changed: 0
wasapi debug: reset
mmdevice debug: state changed: 1
main warning: playback too late (60009): up-sampling
main debug: VoutDisplayEvent 'mouse button' 0 t=8
main debug: VoutDisplayEvent 'mouse button' 0 t=9

mentioned in issue #27059

Hi! I am experiencing the same issue with webex recordings. It forced to use another video player.

Please share a sample.

well I shared video beforehand isn't that enough to work on? you want another sample?

Yes, more people with more samples.

I've uploaded a file at: https://streams.videolan.org/upload/ but i didn't get any receipt or link to send here

But you have another sample! I can upload more if you want

expired. will close without sample

up

I confirm I have the same issue with webex recordings. I'm on intel mac running Monterey 12.5.1 with vlc 3.0.17.3

Same issue here, still with Webex recordings.

I have a sample that I can supply for this problem. Can you supply me with an upload link? The file size is 18.4MB

https://streams.videolan.org/upload/

I wanted to follow up and see if the sample that I provided was helpful and if you've been able to see what may be causing the issue.

Are there any updates to this issue? Please let me know if i can provide more information.

I too have the same problem. Uploading a recording. Can't hear audio from about the 4 minute mark to 4:15 File name is Brainstorm on ISI replacement analysis and plan next steps-20230428 1758-1.mp4

I might have figured out a rather painful workaround. I used HandBrake to convert the mp4 file created by WebEx to an mkv and this appears to behave properly in VLC.

Hi @mahadea, does this still work for you? I tried to do the same but it didn't fix the issue - did you use any specific settings when converting from mp4 to mkv?

Nothing specific, settings wise. I didn't do extensive QA but I picked the one file I had problems with the audio and after conversion I could hear w/o any problems.

fragmented

likely another encoder that can't follow spec and align segments

added Component::Demuxers label

assigned to @fcartegnie

removed Component::Demuxers label

added Component::Demuxers: MP4 label

Webex\ Application\ Pre-ITPilot-20220909\ 1331-1\ (1).mp4

mdat had still 263468 bytes unparsed as samples at @684821

Should map to start of segment 2 for audio on track 2

938 960512 - 0:00:30.016 960512 - 0:00:30.016 684821 307 2 true 0 2 0 0 0

mentioned in merge request !3719 (merged)

I also have the same issue. It was very frustrating. I kept complaining to the person recording the sessions that there must be microphone issue or internet issue on his side now I got confirmation that this is a vlc issue. Have we found any solution? Or is it gonna be resolved in the next update?