[mythtv] [mythtv-commits] mythtv branch master updated by peper03. v0.28-pre-2360-gf54d267

Warpme warpme at o2.pl
Tue Nov 4 09:16:54 UTC 2014

On 04/11/14 00:48, Mark Spieth wrote:
> On 31/10/2014 8:07 AM, Git Repo Owner wrote:
>> The branch, master has been updated on the
>> mythtv repository by gitolite user peper03.
>>         via  f54d2672f224ba24224c8edd12fb0318797b3425 (commit)
>>        from  0bf91f1af368f3aff75d8f1af505c33b4f57052a (commit)
>> Those revisions listed above that are new to this repository have
>> not appeared on any other notification email; so we list those
>> revisions in full, below.
>> - Log -----------------------------------------------------------------
>> commit f54d2672f224ba24224c8edd12fb0318797b3425
>> Author:    Richard Hulme <peper03 at mythtv.org> at Thu, 30 Oct 2014 
>> 22:04:57 +0100
>> Committer: Richard Hulme <peper03 at mythtv.org> at Thu, 30 Oct 2014 
>> 22:07:06 +0100
>> URL: 
>> http://code.mythtv.org/cgit/mythtv/commit/?id=f54d2672f224ba24224c8edd12fb0318797b3425
>> Limit audio buffer to 700ms.  This prevents the frontend locking up 
>> when trying to stop playing an audio-only stream (e.g. DVB radio).  
>> Without this patch the buffer tends to fill to around the 1500ms, 
>> which is below the current 2000ms limit, and AvFormatDecoder never 
>> leaves GetFrame.
>> Normally AvFormatDecoder::GetFrame is exited when a video frame is 
>> decoded.  In this case the audio buffer is usually no more than about 
>> 500ms full.
>> Also, buffering less audio data means less lag is noticeable when 
>> altering the volume if software mixing is used.
> Ive just updated to latest master so I can try out helens mcf patches 
> and noticed a big issue.
> This particular commit causes AV sync problems with high A/V timestamp 
> distances in streams as the audio and video buffers are used to absorb 
> these differences when aligning audio and video at display time, 
> depending which is lagging in the stream.
> It seems to affects HD and higher compression streams (e.g. mp4s) more.
> It will also affect those which use digital audio out (6ch) and use 
> surround synthesis as this incurs a large processing latency for which 
> 700ms is very inadequate. I have set this now to 3000ms in my build as 
> even at 2000ms I'm still getting jerky/skippy playback for HD channels 
> but have yet to test what is optimal. This may warrant a DB setting so 
> that it can be tweaked to find what is best, though worst case is what 
> we need to find out.
> Audio only streams should be handled distinctly to limit the audio 
> output buffering which is what mythmusic originally did.
> mark
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Just another data point.
I also have A/V sync problems by this change. It is on some SD TV channels.
Reverting it solves issue.

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