DTS stutters and sounds like a robot

[mkvguy]

Please help, I've got the following problem:

All my videos play fine as long as they don't have DTS audio (for example: mp3, wma, ac3, etc all play fine). So when a video has DTS, then the audio sounds broken (stutters, sounds like a robot).

Any ideas please?

[mkvguy]

ok I solved all my stutter problems, it took me several hours but I found the problem:

Apparently, mencoder's AC3 encoder is JUNK! I've confirmed it in other forums and in IRC, the AC3 encoder is junk.

Since I don't know how to tell PS3 Media Server to output audio in another codec, I found a small hack:

Under "Expert Settings", add the following line:

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container == matroska :: -lavcopts acodec=libmp3lame


Since it appears at the very end of the command line, it overrides the default "acodec=ac3" and thus all output is in MP3 format. This way there is no stutter, no a/v sync problems no nothing!!!!

[mkvguy]

I did some more research about this problem, it seems like most stutter and audio sync issues are due to this bug (with the exception of those who have underpowered computers).

It appears that people bypass the problem when they enable "Remux when audio track is AC3", but:
1) that only works if the source has AC3 audio, all the rest will play badly.
2) still doesn't solve the problem of broken AC3 encoding

So, I did some more searching and I found out that there are even more problems with 6.1 channels and AC3. For example, the speech ends up on one of the two stereo channels, thus audio sounds weird. Based on various forum threads and some mailing lists, I traced the problem to the AC3 encoding in mencoder. Apparently the AC3 encoder is broken in various ways depending on the mencoder version, and thats why some people have more problems than others.

In other words, I found out that by using mp3 in the output to the PS3 will solve ALL audio issues (unless your computer is underpowered of course). It seems possible to use alternative AC3 encoders, but I haven't found a way how to do that without messing with the source code of PMS.

It is possible to use other audio codecs for the output, for example PCM or whatever your player supports (TV, PopcornHour, PS3, etc). I stuck with MP3 because it worked out-of-the-box for me without any sync issues.

I'm hoping to hear from others with audio issues and their experience with this parameter.

PS:
The way I constructed the parameter, is that it is used ONLY on mkv containers, so .ISO or .AVI or whatever will not be forced into mp3 output. A better way would be this: Enable "Remux when audio is AC3" and use this instead:

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acodec != ac3 :: -lavcopts acodec=libmp3lame


The above will only be enabled when the source audio is not AC3 (thus it will be converted to MP3 and work without audio problems), and when the source audio is AC3 then it will be remuxed and passed to the player directly.

[Madoka]

I just tried both of the above options on an r550 build. I get no sound with both options on mkv files. Am I doing something wrong? Perhaps it's a different version of mencoder?

[mkvguy]

Your mencoder must be compiled with the library "lame", otherwise you may try using a different library. I'm using Linux with the mplayer/mencoder packages created by ATrpms.net for Fedora Linux.

[mkvguy]

Here is another solution if you don't have the lamemp3 library compiled, use mp2 which works everywhere:

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acodec != ac3 :: -lavcopts acodec=mp2


Let me know if it works for you.

[durden]

I had the same problem on Fedora 15. The configuration with option mp2 solved my problem.
Thank you!

[mkvguy]

I'm glad this helped.

Here is an improved version:

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acodec != ac3 :: -lavcopts acodec=mp2:abitrate=384


(this is because, sometimes the audio will have a strange or very high bitrate which is not supported by MP2, thus the above line also forces the bitrate to be set correctly)