Audio distortion in 15.1.1

Source file:
MP4 from sony camera: H.264 + AAC 48kHz

If this file is added to timeline1 everything is OK (playback in resolve and/or when rendered)

But if this timeline1 is added to timeline2 the playpack in resolve is still OK, but when rendered the distortion / clipping is present. It occours after few seconds (

)

Same issue in 15.1.2

Hi there, I have a similar issue, with audio distortion on the rendered file.

To simplify, I used the YouTube output preset (video: 1920x1080 HD H.264 / audio: Linear PCM) with no adjustment to any default output settings. In the Delivery page, just playing a clip, the audio is just fine. However, after rendering, the audio in the output file is clipped/jumpy after about 10 seconds of playback of the rendered file.

Doing some research, I have found the following: -

1) It only seems to occur when rendering clips that have been turned into compound clips.
2) It occurs when rendering MP4 and MOV clips that use an AAC codec. MP3 audio files seem okay.
3) It is okay using version 15.0.1, but becomes a problem after installing any later version, up to 15.1.2.

As an extra test, I took one of the MP4 source files, and re-encoded it to a MOV file with H.264/Linear PCM, turned that into a compound clip, and this rendered with no audio issues. I then took an MP3 file and converted it to an MP4 file with AAC codec, and once converted to a compound clip, the rendered output had the audio issue after 9-10 seconds.

So, to summarise, the audio distortion occurs when rendering an output file that is based on a video clip that uses AAC audio codec, but only if that clip is turned into a compound clip before rendering.

Anyone want to have a crack at duplicating?

So, ummmm, has anyone out there got a few minutes to throw an MP4 that has an AAC audio codec onto a blank timeline, make it a compound clip, render one minute of it out to the standard YouTube Quicktime preset, and check if the sound quality decreases after a few seconds...? Or maybe any suggestions...

After all, I don't want to get perpetually stuck on version 15.0.1

Hi again... hmmm, no replies yet.Progressing further with investigations...

I just did a two minute test to see if I could also duplicate the original poster's issue, and I can. This distorted audio also occurs for a video with AAC audio codec that is placed on a timeline, and that timeline is nested in another. When the second timeline is rendered, the resultant file has audio issues after 9-10 seconds. This is the same effect as when trying to render that file as a compound clip.

I have written to support on this, and no answer. I have now written three replies to the original poster of this, and no answer from anyone else, despite more than 100 views... One could get rather despondent

I guess I will give it another day and then perhaps the best thing is to re-post this a new topic thread with a more 'urgent' title But, in the meantime, if someone could try to duplicate this issue, I would be most grateful... Here is what we are trying to solve: -

After producing a standard YouTube 1080p output file that is rendered from on an input video clip that uses an AAC audio codec, the audio is fine. However if that input video clip is either turned into a compound clip, or is used in a nested timeline, the resultant rendered output file has audio distortion from 9-10 seconds into the clip.

Many thanks for anyone that can confirm they have tried this and whether or not they have the same issue.

AAC isn't really a professional format for use as an intermediate in media workflows. It's a consumer-grade distribution codec. The workaround is just to transcode everything to uncompressed WAV files and use those instead.

AAC isn't really a professional format for use as an intermediate in media workflows. It's a consumer-grade distribution codec. The workaround is just to transcode everything to uncompressed WAV files and use those instead.

+100

AAC isn't really a professional format for use as an intermediate in media workflows. It's a consumer-grade distribution codec. The workaround is just to transcode everything to uncompressed WAV files and use those instead.

Appreciate that Seth. Yes, of course, in a professional world, recording to the highest quality would in fact be the best route, but encoding intermediates to a higher quality is the next best option. In terms of a workaround, given the issue I was seeing, the easiest option was just to select all composite clips and decompose, allowing a render with no audio issues.

+100

Thank you so much Jean Claude for your helpful contribution...

While it is an excellent idea to encode higher spec intermediate clips prior to editing, DR is meant to be a multi-format NLE. If it is as such, some of those 'unprofessional' users out should be able to expect it to be working accordingly.

So, back to the matter at hand. I originally was trying to help out the original poster and see if it was related to a similar problem I was seeing, which turned out to be so. And while workarounds exist, if there is one audio codec that is affected by either nesting timelines or using compound clips, it is possible that this bug could in fact affect other codecs that we haven't tested yet.

I had hoped other users could test this issue to help ascertain if there was a universal issue that BMD should look into. This is what I hoped these forums would be good for. But alas, as no one else has helped test this issue, I can only now leave it at that. I have sent all information to support and trust they will be able to resolve this issue.

.../...
While it is an excellent idea to encode higher spec intermediate clips prior to editing
.../...

@easycass

Without leaving Davinci Resolve for TL that have audio AAC sources:
Provided to do an intermediate step:
Fairlight TAB => Timeline Menu and follow the steps on the image
At the end of these steps: we can use this TL as nested TL.

mix to new track.jpg

At the end of these steps: we can use this TL as nested TL.

Hi Jean Claude, thank you for the additional method to workaround this issue. Appreciate your efforts of course...

I guess in the end, I do realize there are a number of ways to bypass this problem, but the more important point is surely that in v 15.0.1, video using the AAC audio codec that is turned into a compounded clip all rendered fine, and from 15.1.1 onwards it does not. I do not imagine that producing distorted audio is by design, so I would only hope that BMD would be interested in this as a possible bug so that it can be fixed.

People would be screaming if their ProRes/LPCM clips caused distorted audio on rendering. The fact that this happens with a clip that uses a consumer-based audio codec makes it no less important; no less of a bug. And further more, wouldn't all those professionals out there want to know for sure that no other audio codecs are being affected?

I can't believe sometimes how hard it is on these forums to post a possible bug

Thanks again...

I can't believe sometimes how hard it is on these forums to post a possible bug
Thanks again...

Hello,

Not a bug: AAC is not an editing format, it's more like a delivery format: that's it

Not a bug: AAC is not an editing format, it's more like a delivery format: that's it

From Wikipedia: A software bug is an error, flaw, failure or fault in a computer program or system that causes it to produce an incorrect or unexpected result, or to behave in unintended ways

From an video engineering point of view I totally agree with you that it is not good practice to use AAC as an audio codec within the editing framework, but from a software engineering point of view, something that worked in one version but fails to work in the next version is a 'software bug'.

You, of course, may call it what you like.

easycass:
My source file is indeed with AAC audio encoding. And I was able to recreate bug with compound clip (it really looks like that nested timeline and compound clip is internally the same thing).

everybody else:
If Resolve supports AAC codec (which it obvious does) then it should work in all cases. And because it doesn't we have a bug. And all excuses of type "this is not professional bla bla" are just that excuses.


If you have a car, which falls apart after driving on unpaved road with radio turned on, the excuse about unpaved road is not a professional highway is just as meaningful as above.

...(it really looks like that nested timeline and compound clip is internally the same thing).

everybody else:
If Resolve supports AAC codec (which it obvious does) then it should work in all cases. And because it doesn't we have a bug. And all excuses of type "this is not professional bla bla" are just that excuses.

Hi Damijan,

Thanks for the update. Yes, I am hoping that support will pick up on this issue. I agree fully with your view on the software, in that if it is meant to be a multi-format NLE, with specifications that say it handles AAC audio formatted files, then this functionality should work. I am sure it is just a small bug that crept in between version 15.0.1 and 15.1.1, and they can fix it fairly easily.

As to the other point, I do believe that in a forum, while best practice and workaround solution suggestions are most welcome, these should not negate or overshadow the identification of software issues that need addressing. Unfortunately, it is the nature of forums that people lose sight of the original poster's intent due to their own agendas...

If I get a reply from support, I will post it here. Cheers, Cass.

[Peter Chamberlain]

Can someone provide a link to a 10sec source clip we can use to repo this issue.

Are you on Win 10?

Hi Peter,

To summarise, corrupt audio is heard 9-10 seconds into a clip that has been rendered from a source clip (MP4 - MPEG4/AAC) that has first been turned into a compound clip, or used in a nested timeline, and then rendered as a simple H.264/LPCM MOV file. This was not a problem using version 15.0.1, but became a problem after installing any later version, 15.1.1 and 15.1.2.

Here are Dropbox links to three clips: -

1 - Original File - MP4(MPEG4/AAC 30FPS)
https://www.dropbox.com/s/syd8pll4redqe ... l.mp4?dl=0

2 - Rendered File From Timeline - YouTube Output Preset - MOV (H.264/LPCM 24FPS)
https://www.dropbox.com/s/byinr1x0uihdi ... d.mov?dl=0

3 - Rendered File From Compound Clip - YouTube Output Preset at 24 FPS - MOV (H.264/LPCM 24 FPS)
https://www.dropbox.com/s/icunwjwfr200q ... d.mov?dl=0

The only difference between files 2 and 3 is that the latter clip has been rendered from the source clip that was first turned into a compound clip before being rendered. You will hear the distorted audio in file 3 at around 10 seconds.

You shouldn't need Dropbox to download them... See my signature for the system spec.

Cheers,
Cass.

I see now another possibly related post: -

viewtopic.php?f=21&t=81386

my isue seemed to be affecting multicam clips and those were the ones that were getting screwed up so i flatted the multi cam and it has solved it im so happy. it was driving me mad

this post has been really helpful for me to narrow down the problem so thanks everyone

my isue seemed to be affecting multicam clips and those were the ones that were getting screwed up so i flatted the multi cam and it has solved it im so happy. it was driving me mad

this post has been really helpful for me to narrow down the problem so thanks everyone

Yes, either encoding source files to a different format, flattening content, decomposing compound clips and avoiding nested timelines are all good workarounds. Glad that solved it for you.

Hopefully this will eventually get fixed so we don't have to use the workarounds...

Update

I received a reply from Support: -

Blackmagic have said the developers are aware of this issue and are looking in to it. Thank you for the report.

I am having the exact same problem.

From my reddit post on r/blackmagicdesign
"https://youtu.be/LA9 m054rUg4

This is part of a twenty minute video. My voiceover sounds fine throughout the whole thing but everything else in terms of audio (that play fine in Davinci itself) get all choppy.

Rendering JUST the gameplay clips you see here makes them sound fine.

The footage varies from 30fps to 60fps but that shouldn't effect the sound. The video is fine throughout.

I've tried rendering as mp4 aac (which you see here), mov pcm, dxhd... Probably getting these names wrong but it just makes me so frustrated, nothing here is working and I can't find any solutions.

The only things I can think of is that I used retime controls to slow down one of the clips earlier in the video. But again, everything sounds fine in the preview, not in the render.

I've also tried unticking frame reordering but that doesn't seem to effect anything.

Any advice? This whole video I put a lot of time into and I'd really hate to just have to give up because I can't find a solution for this."

I am having the exact same problem.
Any advice? This whole video I put a lot of time into and I'd really hate to just have to give up because I can't find a solution for this."

If this is due to the same problems we have seen, then, until this bug is fixed, you can try: -

1. Transcode your source video file to a different file type (eg .MOV) and video/audio codecs (eg DNxHD/LPCM) - you can use the Media Management in the File menu.

or

2. Make sure your timeline containing the source video/audio is not nested or turned into a compound clip.

Let us know how you get on...

I also have this issue. Support issue #QCP-380-17967.
It's still there in version 15.2.0.033.
Definitely something to do with turning one or more clips into a compound clip.

I also have this issue. Support issue #QCP-380-17967.
It's still there in version 15.2.0.033. Definitely something to do with turning one or more clips into a compound clip.

Yes ... hopefully a fix will make it into the next update.

As a workaround I tried this just before rendering.
I unlinked the audio and video tracks,
then right click on the audio track and do Decompose In Place.
Then did the render.
This cleared up a lot of the clicking, but there is still a little distortion at 9.3seconds in. See attached screenshot of the rendered files audio using WavePad from NCH Software.

still small distortion 9sec in after Decompose In Place of audio.png (143.02 KiB) Viewed 17678 times

As a workaround I tried this just before rendering.
I unlinked the audio and video tracks,
then right click on the audio track and do Decompose In Place.

Yes, there are a few ways around it I guess. As I mentioned above, I found the best things that worked was to either transcode the clips using a different audio codec on ipnut, or if possible, just don't nest or compound the affected clip.

I did the latter recently on a 2 hour production I was working on. It didn't take long to decompose in place all the compound clips, which, once rendered on a straight timeline, came out fine.

Not much else at this stage...

I found the best things that worked was to either transcode the clips using a different audio codec on ipnut, or if possible, just don't nest or compound the affected clip.

Yes I'm looking into the transcode workaround now, but need to check I can do this to some of my more complex projects done recently. I guess it's not a problem if starting a project from scratch.

I'm afraid not using compound clips is not an option for me as I've found it to be the only reliable way to do Multicam and it is a significant part of my workflow.

I have generated three test case projects for Blackmagic Design to have a look at. I hope it will help them debug the issue: https://www.dropbox.com/sh/w5gcq6u0n1vm ... lRHqa?dl=0

Re the transcode workaround, I can now confirm that this is a good workaround.
However while checking it out I found that in version 15.2.0.033 I could not get the "Preserve folder hierarchy after ? levels deep" mechanism to work as expected, and the reference manual doesn't seem to give accurate information. I had to transcode each file containing AAC audio to Linear PCM and place those versions outside of the project folder for the original files. I ended up putting them on another drive and had to reconstruct the media folder hierarchy myself.

I’ve posted my own topic. I think it’s a compound clip problem as my audio is already in WAVs, and my problem is in playback instead of render out.

i have same problem

1) if i use mp4 video with variable AAC bitrate. i have distortion after render. i can solve this problem by transcode source to mp4\constant AAC bitrate.

2) if i use compound clip i have distortion after render aac. i can solve it by uncompound all clips before render. but it is not cool

i have same problem

1) if i use mp4 video with variable AAC bitrate. i have distortion after render. i can solve this problem by transcode source to mp4\constant AAC bitrate.

2) if i use compound clip i have distortion after render aac. i can solve it by uncompound all clips before render. but it is not cool

The issue has been raised with Blackmagic Design support and here's the last I heard:
"our development team are aware of this behaviour.
It only appears to occur with files that have used AAC encoding on their original audio tracks.
We are hopeful that this will be addressed in a future release of Resolve however we are unable to give any timescale for such a release.
In the mean time I would recommend transcoding your files to an alternative codec before importing them into Resolve."

I was about to write audio issues here as well. For two nights trying to resolve issue with "click and crack" sound heard every now and then on rendered clip. Uploaded sample file to Youtube and then noticed something odd. Audio was OK!

So in my case it seems that Windows 10 default Media Player was not able to play the output file properly for some reason. I tested VLC Player then and there it worked okay.

I have no previous experience of Resolve, new user and immediately encountered issues. Luckily Im OK playing files with VLC and Youtube.

So if some others are looking solutions to similar problem, try other video player too and check if that makes any difference.

Just to confirm that issue is stil present in 15.2.2
@AdventureForester: my issues are present in VLC and youtube...

So, to summarise, the audio distortion occurs when rendering an output file that is based on a video clip that uses AAC audio codec, but only if that clip is turned into a compound clip before rendering. Anyone want to have a crack at duplicating?

Yes, exactly the same here on Studio 15.2.2 ... bloody waste of life. Have been trying to render a final 20 min short film for some time now; always distorted and in this case, music plays a big part. Variety of sources and formats, but the bootom line seems to be the use of a Compound Clip - which I used for a final film grade. In every case, the compound clip makes the audio distorted and unusable; upack the CC and all is fine. CC is far more trouble than its worth.

Yes, a bit of a nuisance. Either one has to transcode to another format, or avoid compound-clips and nested timelines. While many pros will undoubtedly go with option 1, with so many cameras using AAC as the audio codec, I do believe it is a bug worth fixing.

I ran into this issue with 15.2.2.

I had to de-compound the audio clips and seemed like it worked.

This still seems to be an issue in version 15.2.4.006... unfortunately.

I now transcode any of these rather popular, yet considered 'amateur' formats, into something more suitable. But perhaps it is better in the long run for Blackmagic to just take the advertised facility out completely, making sure that in the system requirements for DaVinci Resolve Studio it stipulates that 'AAC input audio formats are not compatible with this software'.

But perhaps it is better in the long run for Blackmagic to just take the advertised facility out completely, making sure that in the system requirements for DaVinci Resolve Studio it stipulates that 'AAC input audio formats are not compatible with this software'. :(

Seems to be isolated to the Windows platform, as this issue is not reproducible on my systems with Compound Clips and AAC streams.

Renders always null with the source.

Seems to be isolated to the Windows platform, as this issue is not reproducible on my systems with Compound Clips and AAC sources. Renders always null with the source.

That is good to know. Haha, I knew I should have bought a Mac ...

It has been many months since this was first reported and acknowledged by BM as something they will address in a forthcoming update, so I am hoping they will fix it eventually. It is just a little disheartening every time I do an update to find the same bug remaining...

Go well...

Here on windows 10:

I just redo a test with a canon clip C300 Mark II .MP4 + source sound:

Code: Select all

audio
ID: 2
Format: AAC LC
Format / Info: Advanced Audio Codec Low Complexity
Codec ID: mp4a-40-2
Duration: 3m28s
Source duration: 3m28s
Bit rate mode: Variable
Bit rate: 317 kb / s
Maximum bit rate: 383 kb / s
Channel (s): 2 channels
Channel layout: L R
Sampling rate: 48.0 kHz
Frame rate: 46,875 FPS (1024 FPS)
Compression mode: Lossy
Stream size: 7.88 MiB (1%)
Source stream size: 7.88 MiB (1%)
Language: English
Encoded date: UTC 2015-10-01 02:31:15
Tagged date: UTC 2015-10-01 02:31:15


Delivery in MP4 + ACC and no issue.

@easycass: Can you share a clip that has an issue? (for a test because I can not reproduce)

Here on windows 10:

I just redo a test with a canon clip C300 Mark II .MP4 + source sound:

Delivery in MP4 + ACC and no issue.

@easycass: Can you share a clip that has an issue? (for a test because I can not reproduce)

Greetings again Jean Claude, I had posted some clips previously for Peter Chamberlain to look at in an earlier post above. They can still be found here: -

1 - Original File - MP4(MPEG4/AAC 30FPS)
https://www.dropbox.com/s/syd8pll4redqebv/1%20-%20Movie%20-%20Original.mp4?dl=0

2 - Rendered File From Timeline - YouTube Output Preset - MOV (H.264/LPCM 24FPS)
https://www.dropbox.com/s/byinr1x0uihdi4y/2%20-%20Movie%20-%20Rendered.mov?dl=0

3 - Rendered File From Compound Clip - YouTube Output Preset at 24 FPS - MOV (H.264/LPCM 24FPS)
https://www.dropbox.com/s/icunwjwfr200qq7/3%20-%20Movie%20-%20Compound%20Clip%20-%20Rendered.mov?dl=0

The first is the original clip, the second is rendered from the timeline directly and shows no issues, and the third is rendered from the clip after being turned into a compound clip. The last one shows the audio distortion at around 9 seconds...

Do let me know if you have any issues downloading the files.

Cheers,
Cass.

Do let me know if you have any issues downloading the files.

Cheers,
Cass.

Hello easycass,

(no issue for downloading the files. Thank's)

My tests :
1 - Import your original clip in a new project (default 24 fps= Davinci Resolve ask : change to 30 fps => OK (original clip is 30 fps)

2 - Rendered File From Timeline - YouTube Output Preset - MOV (H.264/LPCM 30 FPS)

3 - Import the YouTube Output Preset clip in a TL (same project)

4 - change it to compound clip

5 - Rendered File From Compound Clip - YouTube Output Preset MOV (H.264/LPCM 30 FPS)

Result : https://drive.google.com/open?id=16ad_f ... dyoBLKBym0

Next new projet :
1 - Import your original clip in new project (default 24 fps= Davinci Resolve ask : change to 30 fps => NO => TL is 24 fps. Player is 24 fps

2 - Rendered File From Timeline - YouTube Output Preset - MOV (H.264/LPCM 24 FPS)

3 - Import the YouTube Output Preset clip in a TL (same project)

4 - change it to compound clip

5 - Rendered File From Compound Clip - YouTube Output Preset MOV (H.264/LPCM 24 FPS)

Result : https://drive.google.com/open?id=1ktTkK ... AxKHRXDiU4

As a result: no issue here.
(links available for a few days)

Hope this help. (maybe check for driver or??? i don't know... Not easy.. )

Jean Claude,
I put a number of test case projects on Dropbox for BM to have a look at. See my message dated: Tue Nov 20, 2018 2:31 pm

Hope this help. (maybe check for driver or??? i don't know... Not easy.. )

Thank you Jean Claude for your time, I really appreciate it.

Just a small point about the process; I see you doing something a little different compared to those of us having problems. In your steps, I see you are essentially transcoding by using the output file rendered in step 2 as the source of the compound clip. From what I see (please tell me if I have this wrong), you are doing this: -

1. Import original MP4/AAC clip.
2. Render original clip to MOV H.264/LPCM.
3. Import rendered clip.
4. Turn rendered clip into compound clip.
5. Render compound clip to MOV H.264/LPCM.

This is the test workflow I was using: -

1. Import original MP4/AAC clip.
2. Render original clip to MOV H.264/LPCM - this is clean.
3. ---
4. Turn original clip into compound clip.
5. Render compound clip to MOV H.264/LPCM - this is corrupted.

So, yes, it is not a surprise that your method produced a clean result, as the new rendered version of the original clip is a format that works okay with compound clips. What doesn't work is the rendering of a compound clip taken straight from the MP4/AAC file.

Sorry for the confusion. Perhaps, if you have some more time to help, you could try the second workflow and let us know the result?

Many thanks,
Cass.

Did you try to render out the project as audio only to see if the issue persists?

Just a small point about the process....
4. Turn original clip into compound clip.
Cass.

Hello easycass,

Oops, sorry

You're right, I did not see this aspect of your workflow. I retested as you mentioned and no issue here.
The link : https://drive.google.com/open?id=1_p2P0 ... _R_nvrY1JC

It's probably not easy to locate the issue but i hope is a logical explanation

Hello easycass, Oops, sorry, You're right, I did not see this aspect of your workflow. I retested as you mentioned and no issue here.
The link : https://drive.google.com/open?id=1_p2P0 ... _R_nvrY1JC

It's probably not easy to locate the issue but i hope is a logical explanation

Thank you Jean Claude. That makes it more interesting, having some computers affected and some not, and perhaps provides the reason as to why BM has been unable to fix it up to now. The only real clue is that when I load up v 15.0.1, the problem goes away, so it was whatever update occurred just after that where the issue was introduced for some people.

As you say, always a difficult issue to fix. I will just transcode any footage that contains the AAC codec in the meantime... Thanks again

Further Testing: -

For some new information for those experiencing the problem, please check out the following.

In the Render Settings Panel: -

Select Render - Single Clip : The audio distortion occurs after 9 seconds for a compound clip.
Select Render - Individual Clips : No audio distortion occurs.

Trying to ascertain the difference between these two modes, I see the following: -

Single Clip : the render Frame Rate is set on the Video tab in the Render Settings panel
Individual Clips : the render Frame Rate is taken from each individual clip

Also, there is a slight difference in options on the Audio tab in the Render Settings panel, although it seems primarily to do with number of tracks/stereo channels, but may be part of the issue.

This may help in two areas: -

1) It may give BM a further clue into what is happening with this issue.
2) It actually provides another useful workaround for those with the issue: -
... a) Turn all your clips and compound clips into one large compound clip.
... b) Render that single compound clip using the Individual Clips setting.
... c) This still produces a single output file but with no noise distortion.

So, the workarounds are now: -

1) Do not use the AAC codec for audio recording
2) Transcode source files into something non-compressed, non-variable before editing
3) Don't use compound clips or nested timelines with such files
4) Decompose compound clips and nested timelines onto a single timeline before rendering
5) Turn all content into one large compound clip and render using the Individual Clips setting

Hope this all helps someone out

In 15.3 the problem seems resolved

In 15.3 the problem seems resolved

From Release Notes

"If you’re using Windows, DaVinci Resolve 15.3 features better AAC audio handling"

So yep, I can also confirm that in my tests, as of version 15.3.0.008, the issue seems to have been resolved.

Thanks to everyone involved in testing and fixing the issue.