[FFmpeg-devel] [RFC] per format probe buffer sizes

Michael Niedermayer michaelni
Tue Apr 15 18:58:06 CEST 2008

On Tue, Apr 15, 2008 at 06:06:33PM +0200, Benjamin Larsson wrote:
> Hello, while trying to work out how to get dts in wav detection to work 
> properly I found out that there was a problem with the size of the probe 
> buffer. Right now it starts from 2048 and increases the size until a 
> format is detected. And when the wav format is used with a command line 
> like "ffmpeg -i dts.wav test.wav" the format is detected in the first 
> try. And reliable dts detection in a test file I had will need more. It 
> found the first SYNC word after 3072 bytes. So for this to work we need 
> to increase this buffer, one could either do it globally or just for the 
> needed format. Before the actual probing that finds the wav format 
> (utils.c:447) there is another probe (utils:433). My suggestion is that 
> we add a flag and size parameter to the format struct and let this probe 
> call fetch this value so it can be used later in the real 
> probe(utils.c:447). This way we can add per format probe sizes which 
> might useful.
> So what do you think of this idea ?

First i think it is wav and it should use the wav demuxer. And i would like
to hear some argument why this cant work that way.

Second you can add a
if(size<4567) //dts needs that at least so wav - dts differntiation is possible
    return 0;
in the wav probe function to achive what you want


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have never wished to cater to the crowd; for what I know they do not
approve, and what they approve I do not know. -- Epicurus
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