VP17 mp4 with 5.1 audio not shown correctly with so4 compound reader

fifonik wrote on 12/20/2019, 10:58 PM

When mp4 with 5.1 audio added on time-line audio shown on 6 audio tracks: each front and rear stereo channels displayed as two mono audio channels. It should be 4 audio tracks: front stereo, centre mono, LFE mono and rear stereo.

There is no issue if so4 is disabled in internal preferences.

First time I noticed the issue in VP15 a few years ago. I disabled so4 and forgot about it.

I was surprised that the issue still exists in VP17. I have not noticed it straight away as I disabled so4 in VP17 after installation. When I played with enabling/disabling so4 the issue was re-appeared and @Marco. reminded about it.

Steps to re-produce:

1. Create a new project

2. Put M2TS with 5.1 audio onto time-line (you can use my sample file). You will see video track and 4 audio tracks: front stereo, centre mono, LFE mono, rear stereo. Optionally you can normalize audio to better see waveforms:

3. Render it to MP4 using Sony AVC (just an example, I do have the issue when I use other encoders)

4. Create new project

5. Put MP4 file you just created on step 3 onto time-line. You will see video track and 6 audio tracks: two front mono, centre mono, LFE mono, two rear mono:

6. In internal preferences set "Enable so4 compound reader for AVC/M2TS" to FALSE, restart VP and repeat steps 4 & 5. You will not see the issue. Audio will be displayed on 4 tracks. M2TS will work fine as well.

Can anyone confirm the issue?

Thanks.

P.S. Reported, Ticket#2019122017001561

Comments

NickHope wrote on 12/21/2019, 2:29 AM

Thanks for the demo. I reproduced the issue in VP15-17 and added it to the known issues post in the So4 section:

"[VP15+] The front and surround channels in an AVC file with 5.1 AAC audio are wrongly decoded as 4 individual mono channels instead of 2 stereo channels."

Please say if that definition is not accurate.

fifonik wrote on 12/21/2019, 4:56 AM

I think surround is fine. Front stereo and rear stereo channels decoded as 4 separate mono tracks.

Thanks for adding it into known issues list.

NickHope wrote on 12/21/2019, 5:21 AM

I thought "surround" is the official name for the rear 2 channels. The Help seemed to confirm that. Might be wrong as I have no experience of 5.1 audio.

fifonik wrote on 1/6/2020, 4:26 PM

Got reply from Magix:

Discussing this with the dev team it appears that this actually isn't a bug and is a normal behavior for 5.1 audio. The reason you might have only seen 4 tracks in the M2TS is due to the left and right channels being combined into on track.

As stated in my last response this is expected behavior for 5.1 audio, this isn't a bug in the software nor the file thus it won't be fixed.

VEGASHeman wrote on 6/5/2020, 11:53 AM

@fifonik: I checked this issue, both myself, and with our team, and it is definitely a problem as you described. We will work to address this as soon as possible. Thank you for bringing this to my notice, and I apologize for the inordinate delay in handling this correctly.

fifonik wrote on 8/13/2020, 1:12 AM

Looks like the issue is fixed in VP18.

It shows 4 audio tracks for mp4 & m2ts AVC files with 5.1 audio regardless of the Legacy AVC decoder I/O setting (Legacy decoder OFF -- so4 is used, Legasy decoder ON -- compoundplug is used).

@NickHope I think you can remove this from know issues list.

NickHope wrote on 8/13/2020, 5:31 AM

Thanks. Confirmed on my machine and removed from the known issues list. I'll also add it to the release history post.