VPX 17 - Sound error when exporting

SullyPanda76us wrote on 9/7/2020, 6:37 AM

Hi... this is driving me crazy... I have a very strange situation: after exporting movie, at some point of the movie, sound gets very jittered/saturated like when loosing cellphone signal in a call.

Rendering the Same project causes the effect on different places. Mostly after a transition.

This had happened in my last 3 projects, which are very simple: Just one video stream edited by cutting some segments:

I have searched a lot before asking, also readed this post: https://www.magix.info/us/forum/exporting-to-mp4-weird-popping-sound--1252422/

Here is an example:

VPX version: 17.0.3.68

As posted above, I've already did al the different settings (audio buffer / GOP / FrameRate etc). It seems to me more like the program gets corrupted at some point.

Any help would be greatly appreciated,

Thanks,

Comments

SullyPanda76us wrote on 9/7/2020, 7:11 AM

Ok, just installed (fresh) VPX on my second computer.
Copied project + video source = Same problem

Here are the two files, if it is of any help:

https://drive.google.com/drive/folders/170gtQC1E5kKbxbf3FnAQtOXZ8rXECKhs?usp=sharing

johnebaker wrote on 9/7/2020, 9:15 AM

@SullyPanda76us

The issue is with the export settings - the bitrates are 10x what is required for the resolution of video you are exporting - it is probable the player is choking on it.

These are the default settings for 640 x 480 MP4

Try lowering the bitrates to some thing more reasonable especially the Maximum bitrate - 40000 is way to high even for Full HD 1920 x 1080 video.

HTH

John EB

CubeAce wrote on 9/7/2020, 1:28 PM

@SullyPanda76us @johnebaker

Hi.

I don't seem to have access to the files but your 640 x360 is an unusual screen ratio. I also don't understand how you are getting white noise coming from the left and distorted sound from the right. Your GOP structure could also be too long but don't know the original file data. Try 4 sound buffers with the next amount of 16384 in the multi track and Preview size.

Where do the source files come from? Are they all recorded with the same settings? Is the audio at 44kHz or 48kHz? Do they vary between clips?

John. Do you have the files?

To me it sounds like a de-muxing or similar gone wrong or maybe a copy inhibit process.

Odd that the left stays with white noise and the right stays with distorted sound.

Ray.

SullyPanda76us wrote on 9/7/2020, 2:35 PM

@SullyPanda76us @johnebaker

Hi.

I don't seem to have access to the files

Fixed

but your 640 x360 is an unusual screen ratio. I also don't understand how you are getting white noise coming from the left and distorted sound from the right. Your GOP structure could also be too long but don't know the original file data. Try 4 sound buffers with the next amount of 16384 in the multi track and Preview size.

Done... problem persist

Where do the source files come from?

Firstly, let me tell again that this is the 3rd project with this problem. Different source in each one.

In this particular situation, the video is a download from social network FB (so i asume it passed all it's quality-reencodes)

(I do have a copyright on the clip, if anyone is worried about that)

Are they all recorded with the same settings?

Yes, because, as stated, is just a big 2-hr clip, that is cutted in VPX to about 5 min

Is the audio at 44kHz or 48kHz? Do they vary between clips?

John. Do you have the files?

To me it sounds like a de-muxing or similar gone wrong or maybe a copy inhibit process.

Odd that the left stays with white noise and the right stays with distorted sound.

I havent realized this left/right thing

Ray.

johnebaker wrote on 9/7/2020, 3:07 PM

@SullyPanda76us

. . . . Rendering the Same project causes the effect on different places. Mostly after a transition . . . .

Using VPX 12 your project loads and exports the selected range perfectly.

However the source video is variable frame rate and while VPX 12 handles it OK, I suspect VPX 11 may not, certainly older versions of VPX did not like variable framerate video, I cannot test VPX 11 as I do not have it installed.

Try converting the source video to constant framerate - Handbrake will do this for you and then import that.

There is no need for the export setting bitrates to be as high as in the project - the exports I did at the resolution of the source video has an average bitrate of 8000 kbs.

John EB

CubeAce wrote on 9/7/2020, 3:10 PM

@SullyPanda76us

Hi Sully.

If you could go to the text view in MediaInfo and post that info, it will have a lot more information on bit rates etc. but at the moment it looks like the size of the file is far too small to hold any quality of video or audio for that length of clip.

I've not tried downloading anything from Facebook so I'm not sure what they do. As for copyright, that's none of my business. Is there a download facility or do you have to use something like Firefox to download it?

I ask because Facebook may put a copy inhibit code into the file when they recode it for their platform. That, I'm not sure of but is possible to try to stop people from doing a direct download copy.

Ray.

SullyPanda76us wrote on 9/7/2020, 3:14 PM

@SullyPanda76us

Hi Sully.

[...]

Ray.

Hi Ray!

heres the text output

@johnebaker gonna try that. I'm using VPX 17 anyway

General
Complete name                            : T:\Magix\Video Pro X\MesaCentral.mp4
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom (isom/iso2/avc1/mp41)
File size                                : 379 MiB
Duration                                 : 2 h 1 min
Overall bit rate                         : 436 kb/s
Writing application                      : Lavf56.40.101

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L3
Format settings                          : CABAC / 3 Ref Frames
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 3 frames
Format settings, GOP                     : M=4, N=60
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 2 h 1 min
Bit rate                                 : 365 kb/s
Width                                    : 640 pixels
Height                                   : 360 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Variable
Frame rate                               : 30.000 FPS
Minimum frame rate                       : 29.412 FPS
Maximum frame rate                       : 31.250 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.053
Stream size                              : 317 MiB (84%)
Codec configuration box                  : avcC

Audio
ID                                       : 2
Format                                   : AAC LC SBR
Format/Info                              : Advanced Audio Codec Low Complexity with Spectral Band Replication
Commercial name                          : HE-AAC
Format settings                          : NBC
Codec ID                                 : mp4a-40-5
Duration                                 : 2 h 1 min
Duration_LastFrame                       : -1 ms
Bit rate mode                            : Constant
Bit rate                                 : 64.0 kb/s
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 48.0 kHz
Frame rate                               : 23.438 FPS (2048 SPF)
Compression mode                         : Lossy
Stream size                              : 55.7 MiB (15%)
Default                                  : Yes
Alternate group                          : 1

johnebaker wrote on 9/7/2020, 3:23 PM

@SullyPanda76us

. . . I'm using VPX 17 anyway . . . .

Do you mean the latest version - VPX 12 or the version you originally had ie v17.0.3.68 which is VPX 11 ?

John EB

CubeAce wrote on 9/7/2020, 3:58 PM

Thank you for the info.

Well the sound in theory should work. You are at the lowest end of the bitrate the HE-AAC codec can expect to handle two channels of audio.

Is this info from one of your exported files? I notice the frame dimensions are 640 x 360.

That has confused me if it is an exported file as it has a variable frame rate.

Have you tried upping the audio to 160 or 192kbps if it is a VPX export?

You may still get white noise on the left channel but in VPX you can split a stereo channel and use just the right channel if the higher bit rate gives you a cleaner sound.

But as I say, I'm confused if it is an exported file as the files overall bitrate seems smaller than your settings at 365 kb/s.

Ray.

browj2 wrote on 9/7/2020, 10:00 PM

Hi,

I posted this in a similar thread about MEP.

I had a problem with sound at a crossfade in VPX11 recently. Actually, the problem was even more than just the transition.

Try this. Make a range that covers the left and right objects of the crossfade. Solo the audio track (I strongly recommend that you have AV on separate tracks as it's much easier to work with audio). Do a mixdown of the audio using the shortcut Shift+D. This will replace the audio with a red wave file for the range containing only the audio of the soloed track. Unsolo the track. Play back the problem area. Is the glitch still there? If not, export. Glitch gone?

I use transitions often and this was the only time that I recall having a problem with the audio. Strange.

John CB