[vlc-devel] Slow audio when streaming flv

[Dave Still]

I did some more testing on this bug, and it appears to slow down the  
audio for *all* audio codecs selected (tested with mp4a and mpga).  I  
also opened a Trac ticket for the issue:

http://trac.videolan.org/vlc/ticket/1630

Thanks,
- Dave

On Jun 20, 2008, at 4:02 PM, Dave Still wrote:

> So, I finally got VLC compiling for me again on my Mac (thanks,
> Pavlov!), and I'm back to revisit this audio bug.  I tried modifying
> "modules/codec/avcodec/encoder.c" line 578 from this:
>
>         if ( p_enc->fmt_out.i_codec == VLC_FOURCC('m','p','4','a') )
>
> to this:
>
>         if ( p_enc->fmt_out.i_codec == VLC_FOURCC('m','p','4','a') ||
> p_enc->fmt_out.i_codec == VLC_FOURCC('m','p','3',' ') )
>
> and then later to this:
>
>         if ( p_enc->fmt_out.i_codec == VLC_FOURCC('m','p','4','a') ||
> p_enc->fmt_out.i_codec == VLC_FOURCC('m','p','g','a') )
>
> I still get really slow-sounding audio as described below.  I'm using
> VLC as the streaming source for my slingbox-like application
> "TyStreamer". (Which the first revision of actually predates the
> founding of Sling Media! :D )  Everything works great except for this
> audio issue.  Since TyStreamer relies heavily on the 0.9.0 branch of
> VLC, I'm trying to coordinate a release candidate near the release
> test1, and obviously I'd like to have good audio for that release. :)
>
> For the curious, the project is GPL and can be found at http://www.wiskars.com/tystreamer
> .  Latest SVN is recommended.
>
> Thanks,
> - Dave
>
>
> On Apr 16, 2008, at 10:35 PM, Rafaël Carré wrote:
>
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA1
>>
>> Le Wed, 16 Apr 2008 17:59:30 -0700,
>> Dave Still <dave at stilldesigning.com> a écrit :
>>
>>> I finally got VLC git to build on Mac OS X (Intel Leopard with
>>> latest iPhone SDK), and everything works, but the audio is "slow".
>>> Here's the command-line:
>>>
>>> '/Users/stealthdave/Movies/D061219_01/VIDEO_TS/VTS_01_1.VOB' --sout
>>> "#transcode
>>> {vcodec
>>> =
>>> FLV1
>>> ,acodec
>>> =
>>> mp3
>>> ,samplerate
>>> =
>>> 44100 
>>> ,ab=128,vb=256,width=320,height=240}:std{access=http{mime=video/
>>> x-flv},mux=ffmpeg{mux=flv},dst=0.0.0.0:8090/stream.flv}"
>>>
>>> The video plays at normal speed.  Rather than resampling the audio,
>>> vlc is slowing down the audio to match the requested samplerate.  In
>>> order to keep up with the video, vlc is dropping pieces of the
>>> audio. This keeps the video and audio in sync (well done), but makes
>>> videos of my wife sound like James Earl Jones (not so well
>>> done ;) ).  The build was from git latest as of a couple of hours
>>> ago.
>>
>> Can you look in ffmpeg/codec/encoder.c line 571, there is a  
>> workaround
>> for faac, could you try the same with acodec 'm','p','3',' ' ? (or
>> maybe it is 'm','p','g','a' i'm not sure ..
>>
>> - --
>> Rafaël Carré
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