[pulseaudio-discuss] rewind and underrun issues on start of playback

xing wang wangxingchao2011 at gmail.com
Fri May 27 00:52:17 PDT 2011

Hi tanuk,

Let me quote piece of your post:
"Are there any real problems with this rewinding, like the beginning of
the stream disappearing, or an audible drop-out in the audio? The sink
buffer has to be always rewound when a new stream is created, because
initially the sink buffer contains silence. That silence has to be
overwritten with the stream data, so that there's no unnecessary latency
due to waiting for the silence to be played."

If the buffer_size is bigger enough, such as 2s, at the beginning of
stream starting playback, there's only silence, right? For music
playing, it maybe accetable for user.But for
video playing, this obvious delay makes Video/Audio out of sync.

I am not sure whether catch your point clearly.


2011/5/26 xing wang <wangxingchao2011 at gmail.com>:
> 2011/5/26 Colin Guthrie <gmane at colin.guthr.ie>:
>> 'Twas brillig, and xing wang at 26/05/11 10:42 did gyre and gimble:
>>> 2011/5/26 Colin Guthrie <gmane at colin.guthr.ie>:
>>>> 'Twas brillig, and xing wang at 26/05/11 09:09 did gyre and gimble:
>>>>> I: main.c: This is PulseAudio 0.9.22
>>>> Just as a very small aside, David did some work on "Fighting Rewinds"
>>>> recently.
>>>> Just search the stable-queue git log for "Fighting rewinds"...
>>>> These may already be included in your build, but if not it's perhaps
>>>> worth grabbing those patches?
>>> Thank you Colin, let me have a try.
>> Of course it's probably sensible to just run the whole "stable-queue"
>> branch. That's generally what I do in my distro packages... just apply
>> all stable queue patches on top of the official release. A 0.9.23
>> release will likely go out soon (if I can nail Lennart down!) based on
>> this branch.
> Hi Colin, i think my release had include David's patchset.  I see
> there're three patches about "Fast rewind", here's the link:
> http://gstreamer-devel.966125.n4.nabble.com/Fighting-rewinds-pulseaudio-crash-update-td3248107.html.
> The delay issue met based on my release build could not be fixed with
> David's patch.
> But i think it's quite like Ccrma's description in post "rewind and
> underrun issues on start of playback".  If change the buffer size to
> smaller value, the delay becomes short. I am not sure whether alsa is
> playing silence data or just didnot start playback.
> Thanks
> --xingchao
>> Col
>> --
>> Colin Guthrie
>> gmane(at)colin.guthr.ie
>> http://colin.guthr.ie/
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