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

Michael Niedermayer michaelni
Tue Apr 15 19:05:00 CEST 2008

On Tue, Apr 15, 2008 at 06:48:43PM +0200, Benjamin Larsson wrote:
> 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 ?
>> MvH
>> Benjamin Larsson
> Here is a patch describing the idea, for it to work we would need to re add 
>  format extensions for the formats which support/need custom probe size.

This is insane, patch rejected :)
See the solution i suggested.
It doesnt double the read size unless the file really needs it. No weird
file extension tests, no misuse of "value", no API change.

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No great genius has ever existed without some touch of madness. -- Aristotle
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