[FFmpeg-devel] [PATCH] Get rid of SAMPLE_FMT_S24

[Justin Ruggles]

Baptiste Coudurier wrote:
> Michael Niedermayer a ?crit :
>> On Sun, Nov 18, 2007 at 02:35:17PM +0100, Baptiste Coudurier wrote:
>>> Hi
>>>
>>> Andreas ?man a ?crit :
>>>> hi,
>>>>
>>>> see $subj
>>>>
>>> Some codecs support 24 bit (alac, flac, aes3, dvd) samples, decoders 
>>> should output what is stored, ideally, so I don't see why SAMPLE_FMT_S24 
>>> should be dropped.
>> there are no 24bit ints stored, what is stored are various vlc codes
>> outputing them as 32bit is faster and more natural than 24bit
>> also working with 32bit is a lot easier than 24bit, so few if any filters
>> would support 24bit ...
> 
> There are 24 bits ints stored, in dvd pcm and aes 3 at least.
> 
> You are IMHO messing up sample format and stored format.
> SAMPLE_FMT_S24 depicts the sample value range is using 24 bits.
> 
> I still don't see why SAMPLE_FMT_S24 should be dropped.
> 
> In contrary I think a better mechanism should be added, like 
> WAVEFORMATEXTENSIBLE does, if you want to tell application that sample 
> is on 24 bits but stored on 32 bits.
> 

How about:
AVCodecContext.sample_fmt = SAMPLE_FMT_S32
AVCodecContext.bits_per_sample = 24

I tend to agree with Michael here.  Working natively with 24-bit samples 
is not very useful or easy.

-Justin