Re: [Libquicktime-devel] [PATCH] chunk_to_offset and PCM 'sowt' fixes

[Burkhard P. <bur...@ig...>]

Hi,

Am 07.05.2013 11:47, schrieb Erik Johansson:
> Hello,
>
> On Tue, May 7, 2013 at 11:33 AM, Burkhard Plaum
> <bur...@ig...> wrote:
>> How sure you about that? Do you have any sample files?
>>
>> I can remember double-checking the sample formats a while ago, and it turned
>> out that 8 bit PCM seems *always* unsigned, even if the name sowt (twos backwards)
>> suggests something else.
>
> I came across this on movie files created by a Panasonic FX35 compact
> camera. There's a sample file at http://goo.gl/2RtVy (link to google
> drive document, use File->Download to get a non-streamed version). I
> used google to try and find out what the right thing to do here was
> and ended up at http://wiki.multimedia.cx/index.php?title=ADPCM, so I
> may well be wrong. I wouldn't be surprised if some encoders do the
> wrong thing here.

Of course there are always encoders who do the wrong thing. This way
hacking on multimedia libraries at least doesn't become boring.

I didn't find any reference regarding 8 bit sowt so I changed the
sample format to signed as you suggested. Maybe the camera you mentioned
is the only encoder which writes 8 bit sowt anyway :)

Burkhard