Some files have no sound, some can't play video.

[n1kk]

I've tried to run the ugly demo project with prebuilt binaries under Linux (Ubuntu 21.04) and it has inconsistent playback behavior. Some files play fine, some have no sound, some have no video.

In logs I can see that it fails to find/load codecs, but the VLC itself is playing those videos just fine.

@RSATom Can you help me figure out how to solve this?

In logs for missing audio I can see Codec 'eac3' (A/52 B Audio (aka E-AC3)) is not supported

looking for video decoder module matching "any": 15 candidates
using ffmpeg Lavc58.91.100
CPU flags: 0x000fd3db
allowing 6 thread(s) for decoding
codec (h264) started
using frame thread mode with 6 threads
using video decoder module "avcodec"
looking for packetizer module matching "any": 25 candidates
using packetizer module "a52"
looking for audio decoder module matching "any": 20 candidates
reusing audio output
too low audio sample frequency (0)
keeping audio output
failed to create audio output
using ffmpeg Lavc58.91.100
CPU flags: 0x000fd3db
codec not found (A/52 B Audio (aka E-AC3))
no audio decoder modules matched
Codec `eac3' (A/52 B Audio (aka E-AC3)) is not supported.
Codec not supported
VLC could not decode the format "eac3" (A/52 B Audio (aka E-AC3))
killing decoder fourcc `    '
removing module "a52"

In logs for missing video I can find Codec 'hevc' (MPEG-H Part2/HEVC (H.265)) is not supported.

looking for video decoder module matching "any": 15 candidates
using ffmpeg Lavc58.91.100
CPU flags: 0x000fd3db
codec not found (MPEG-H Part2/HEVC (H.265))
no video decoder modules matched
Codec `hevc' (MPEG-H Part2/HEVC (H.265)) is not supported.
Codec not supported
VLC could not decode the format "hevc" (MPEG-H Part2/HEVC (H.265))
killing decoder fourcc `    '
looking for audio decoder module matching "any": 20 candidates
using audio decoder module "faad"
looking for meta reader module matching "any": 2 candidates

[RSATom]

Can you please provide those files for testing?

[n1kk]

Oooh. Those are big files. But I'll see if I can encode some small samples with those codecs to reproduce the issue.

[n1kk]

Here are 4 test files I've made with two video codecs and two audio

• Spring_Blender_Open_Movie_20sec_1080p_h264_aac.mkv: plays video, plays audio
• Spring_Blender_Open_Movie_20sec_1080p_h264_e-ac3.mkv: plays video, no audio
• Spring_Blender_Open_Movie_20sec_1080p_h265_aac.mkv: no video, plays audio
• Spring_Blender_Open_Movie_20sec_1080p_h265_e-ac3.mkv: no video, no audio

All files play in VLC if opened directly.

Spring_Blender_Open_Movie_20sec_1080p.zip

[RSATom]

FYI, I didn't find solution yet but atm I have a feeling Electron applies some restrictions to child process which libvlc doesn't like and can not load some plugins. I'm still trying to find the reason...

[n1kk]

Thanks for looking into it!

Have you tried it on Linux or on other OS (Win/Mac) ?

Wondering if it's Linux specific issue.

[RSATom]

No, I didn't. But I'm sure 90% it's Linux specific.

[n1kk]

I tried disabling sandbox in electron in every way they allow it in their docs but it doesn't help.

Found this MR to electron: electron/electron#15894 something about mixed sandboxing specifically for linux. I'm not skilled enough to figure out if that's related or any helpful at all :(

I also tried building mpvjs project, after eventually succeeding it ended up having exactly the same problem.

[RSATom]

Hm... interesting... Thanks for sharing this info.

[RSATom]

I think I've found the reason and it's old issue: #69 (comment)
In two words: Electron is shipping with its own version of libffmpeg.so and it exports some functions with the same name as libavcodec.so used by libvlc. So libvlc just uses function from wrong .so and it breaks everything...

[n1kk]

Hm, interesting. So what can be a possible workaround here? I've seen some issues that asked how to use custom ffmpeg in electron instead of built in one. Would that be a possible course of actions?

[RSATom]

If you will be able rebuild ffmpeg with all required codecs - then you will not need WebChimera.js at all.
Other possible solution - hack .so import/export tables at runtime to workaround conflicts. But it's pretty complex solution and I don't sure how much effort it could take.