[MPlayer-dev-eng] A strange A-V sync problem of MPlayer-1.0-pre5 ported on ARM920

[Sascha Sommer]

On Wednesday 22 September 2004 13:35, Ed Wildgoose wrote:
> Xu Guangyi wrote:
> >Hi all:
> >     I have just finished a porting of MPlayer-1.0pre5 on Motorola
> > DragonBall MX1 ADS ,the MPU is ARM920 core, with arm-linux-2.4.18 as
> > kernel. I use libmad build for ARM-optimize as the MP3 decode, and
> > ffmpeg's libavcodec as the video decoder.
> >
> >     But, When I use the command like this to play a MP3 file on my board:
> > "$mplayer testMP3.mp3 "
> >     the sound I hear from my speaker was so fast than normal speed...
> >     but when I add "-quiet" after it, the speed is OK.
> >     Why ??  the '-quiet' argument is so strange that the speed of MP3
> > play will "obey it" ????
>
> Hi, it sounds like your audio driver is possibly stuck at the wrong
> rate. Mplayer basically sends the audio to the soundcard as fast as the
> card wants it (assuming that the card is doing the rate that was
> requested), and then we display the video frame after every X audio
> samples have been consumed.
>
> This algorithm means that the video is always shows in sync with the
> audio even if the audio speed is slightly adrift from the real rate
> (which is common with audio cards). In your case you seem to have an
> audio card which is waaaayyy off and hence the whole thing rockets through.
>
> (Oh, and --quiet removes the audio and the video is then clocked based
> on the PC clock not the audio rate, hence it works again)

No, rtfm.
-quiet simply removes the status bar and he is playing a mp3 and not a video 
file. The status bar is using floats so maybe this has something todo with 
it. It sounds more like an audio driver bug, though.

Sascha