Sound 'labouring' on Transcoding on ROKU and Android client

[tobias-tobin 9]

This is after running the mkv through mkvmerge:

ffmpeg

server

file

 

audio still not right.  this time I used chrome.

Edited December 29, 2013 by tobias-tobin

[Tikuf 663]

Ya that is the param that i am looking to change

 

async=1000 will constantly resync the audio throughout the file

async=1 syncs the audio at the start and then leaves it alone

 

what i need to find out is how it impacts on audio drift with other files before i change it in the source

[tobias-tobin 9]

Definitely.  I was wondering about that. It may fix this but break something else, or fix this for a while and then eventually it is out of sync. I'm going to send you a pm.

[Tikuf 663]

@@Luke I have a pull request with this change in it. It will need a lot of testing to make sure we dont get any audio drift. If we do we may have to rethink a little logic

[tobias-tobin 9]

I am curious.  Is the problem really on my end?  Is this a 'bad' file?  If so, should the responsibility to fix it be on the end user?  I don't want transcoding to get messed up because of improperly encoded files.  I know others have posted that they have seen this too, so it is not just me...But again, I don't want to cause you guys to redo transcoding and possibly have new issues because of this.  If it is something I should fix, then I think that is fair.  I'm not sure what I need to do to fix it though   If you have an idea I will try it.  It would also be nice to have a way of identifying the files I have that will have this problem.  I should go to bed now.

[Tikuf 663]

It is a combo of issues. The async=1000 re-samples the audio every millisec and stretches or shrinks the audio to make it fit the decode time stamps of the file which is what causes the warbling effect you are hearing it was put in because we were seeing audio drift in some circumstances (early on with hls in particular due to segmenting) since it was put in the c/l have changed significantly and it has not been touched since.

 

Your file is not wonky per say (in fact it is most likely perfect) but we may see an effect on other files if that is the case we will adapt and make it work for both.

 

That said if Luke commits the pull request I just made the sync on files will need a lot of testing by the alpha team to make sure that everything is ok.

Edited December 29, 2013 by Tikuf

[ginjaninja 533]

Version 3.0.5131.18923

 

This version has eliminated the original issue and the audio is now listenable...however the clients i have tested (web on chrome win7, and android and roku) insert (into the audio tracks exhibiting the original issue) very brief pauses into the the audio track.

Its as if the audio is every so slightly faster (or is that slower?)  than it should be (not so much you can hear the pitch increase), but then every so often the audio has to pause to sync up with the video track (a guess on my part, just guessing what is going on).

 

the test film i am using is "10 things i hate about you", the films starts with music, making the original issue and the new issue more noticeable.

 

Still 1000% times better than it was thank you.

[Tikuf 663]

No this is more likely the audio decoder resetting in between segments. I will play with it but not right now.