Question / Help Audio Bug? Or...

K

Kovlur

New Member
So I have been playing around all day with obs custom output ffmpeg.

The issue I am having is, that I want to record a video that has 6 separate audio tracks.

So I set up Recording tab to custom output ffmpeg, container-mkv> video encoder-libx264> audio encoder-pcm_s24le (wav), and I set the bitrate at 640 kbps.

Then I went to the Audio tab in Output and properly set up every separate audio track, 4 of them are 320kbps one is 512kbps and the other is 640kbps a total of 6 separate audio tracks.

1,5 and 6 tracks are the combined channels of all the sources.

Then I did a little test, recorded 2 videos both 20 seconds. One is set to 640kbps in the Recording tab, and the other video is set to 3502kbps (just for a test).

Both video files contain the audio tracks, but all of the audio tracks are the same kbits 3175.2

I checked with MediaInfo.

Even the file sizes were basically the same, one was 324MB the other 334MB.

So it would seem that, setting the audio bitrate in the Recording tab does not matter, as well as setting the bitrate in the Audio tab in Output does not matter too.

Can anyone help with my issue? I really want to be able to record a video with wav separate audio tracks and still keep the 1,5 and 6 audio track at different bitrates.

Here are the settings:
1.png
2.png
 
I think once you've gone to custom ffmpeg output, the governing audio bitrate setting is the one on the Recording tab, not the one on the Audio tab. I could be wrong, though.

The issue I am having is, that I want to record a video that has 6 separate audio tracks.
Click to expand...

You can absolutely do that! You do need to be in advanced output mode, but I think you've already enabled that.

So I set up Recording tab to custom output ffmpeg, container-mkv> video encoder-libx264> audio encoder-pcm_s24le (wav), and I set the bitrate at 640 kbps.
Click to expand...

Is there a reason your requirements are so particular? All you need to get multitrack audio is turn advanced mode on and check the number of tracks you want.
 
Narcogen said:
Is there a reason your requirements are so particular? All you need to get multitrack audio is turn advanced mode on and check the number of tracks you want.
Click to expand...

Well honestly, my reason is mostly just to test out what can I do with obs.


Narcogen said:
I think once you've gone to custom ffmpeg output, the governing audio bitrate setting is the one on the Recording tab, not the one on the Audio tab. I could be wrong, though.
Click to expand...
But about your message above, I meant that by setting the audio bitrate in the Recording tab in Output with advanced mode as you can see in the picture, MediaInfo showed that both videos with different program set audio bitrate, are the same bitrate in MediaInfo. So that is why I though I had found out some kind of bug.

The Recording tab with the Audio bitrate does not work, no matter which bitrate you set, nor does the bitrate options in the Audio tab in Output.

MediaInfo shows this:
3.png
4.png
 
I mean, is there a reason for the bitrates to be different on tracks 1,5 and 6? For most applications OBS is used for, video content is much larger than audio, most streaming video platforms have reasonable upper bounds for audio track bitrates anyway... you wouldn't be saving much disk space just by reducing audio bitrate on certain tracks.
 
Narcogen said:
I mean, is there a reason for the bitrates to be different on tracks 1,5 and 6? For most applications OBS is used for, video content is much larger than audio, most streaming video platforms have reasonable upper bounds for audio track bitrates anyway... you wouldn't be saving much disk space just by reducing audio bitrate on certain tracks.
Click to expand...
Ohh, I get what you mean. So no, I am just using 1,5 and 6 for testing purposes. 1 is 512, 5 is 640 and 6 is 320. Then I am checking to see if there is any difference in audio quality when uploading on youtube. But then I got this issue which as I said above keeps all the different audio tracks at the same bitrate of 3175.2 kbits, no matter what bitrate I set in any tab.

Also, please check the mediainfo images above this post.
 
I'm not qualified to judge whether or not OBS has a bug in custom ffmpeg output that fails to honor audio bitrate settings.

Normally I would suggest a workaround if a user encountered such a problem, but it seems like you don't actually have a problem, you're just looking for possible mismatches between settings and output.

There might be value posting this in the Development forum? Most of the posters in the Support forum are other users, not devs.

General Development

Questions and discussions of API usage, general plugin development, general OBS development, or yelling at Jim about code.
obsproject.com
 
Is it not an issue, if I can't tell what bitrate I am actually looking at? I tried to see if I could look at the bitrate in audacity, but could not find any option that showed it. One last thing to ask of you, do you know any program, that I could download and look at the true bitrate of a audio?
Otherwise yeah, I will look around the development forum too. Thanks for tuning in to help any way you could.
 
It is an issue, but not one I am used to dealing with.

Custom FFMpeg output is not on by default, it's pretty much "here be dragons" territory where it's assumed someone knows that there are specific results they want to achieve and they know what command line parameters to enter in order to get them.

For regular users, the response to a problem they're having while using Custom FFmpeg output would be to turn that off, and either use regular Advanced or Simple output mode.

YouTube, for instance, just straight up specifies 128Kbps stereo audio. They transcode anything above that to that, so there's no point in giving them more, and since video tracks are much larger, there's no real savings to setting it lower and getting less quality and files that are... about the same size.

You may very well have found a bug, and I'm just a user, not a dev, but the advice of most users if they had a problem in these particular areas would be to avoid custom output unless they had a requirement they could not meet any other way, and just wanting a specific arbitrary audio bitrate wouldn't be one, since there are very few systems that require that but don't do their own transcoding.
 
Yeah, I feel that way too. Made a experiment profile and scene to test out the custom setting, and see what kind of results I could get with it. But with my limited knowledge, so far so good :'D.
Btw, I really want to ask you about that youtube audio bitrate. All day everywhere I search people say different things, some say 256Kbps, other say 128Kbps on AAC. Others say that it's both AAC and Opus, and that the opus bitrate on youtube is 160kbps.
So I wanted to ask, would you happen to know what the bitrate really is? Have you come across the real answer, and what if I then record 128Kbps by your example, and then upload that. Would youtube then re-encode into 128kbps again? And if so, would it not be better to bump up the bitrate to at least double, so when it re-encodes it doesn't lose more quality then with 128 original bitrate.
 
For uploads:

YouTube recommended upload encoding settings - YouTube Help

These features are only available to partners who use YouTube Studio Content Manager. Below are recommended upload encoding settings for your videos on YouTube. Container: MP4
support.google.com support.google.com

Recommended audio bitrates for uploads
TypeAudio Bitrate
Mono128 kbps
Stereo384 kbps
5.1512 kbps

For streaming:

Choose live encoder settings, bitrates, and resolutions - YouTube Help

Choose a quality that will result in a reliable stream based on your internet connection. Read this article to learn how.
support.google.com support.google.com

Recommended advanced settings
Pixel aspect ratio:Square
Frame types:Progressive Scan, 2 B-Frames, 1 Reference Frame
Entropy coding:CABAC
Audio sample rate:44.1 KHz
Audio bitrate:128 Kbps stereo
 
Alright, thanks for the links. I already looked at those support.google.com forms but lost them due to power outage, will bookmark them now :).
Thanks for all the help, have a nice day or night.
 
Holy, I think I just found someone else with the same issue. Also found an answer to the "issue" guess it is a feature, you could take a look at it here:

Question / Help - Unable to ignore bitrate setting with ffmpeg

This has been bothering me for a long time, I am recording utvideo + flac with OBS-FFMPEG in an .avi container. I can't just let ffmpeg use it's default settings for audio/video bitrates I have to actually set a bitrate. Now, when ffmpeg outputs the files it seems to ignore the video bitrate...
obsproject.com
Read all the comments, they are just a few.
Also, anyway to tag this as solved?
 
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