[FFmpeg-devel] [PATCH] fix the SAMPLE_FMT_NONE case in ffmdec.c

[Bobby Bingham]

On Wed, 17 Mar 2010 00:17:46 +0000
M?ns Rullg?rd <mans at mansr.com> wrote:

> Bobby Bingham <uhmmmm at gmail.com> writes:
> 
> > On Tue, 16 Mar 2010 16:38:44 +0000
> > M?ns Rullg?rd <mans at mansr.com> wrote:
> > [...]
> >> >>              codec->sample_rate = get_be32(pb);
> >> >>              codec->channels = get_le16(pb);
> >> >>              codec->frame_size = get_le16(pb);
> >> >> -            codec->sample_fmt = get_le16(pb);
> >> >> +            codec->sample_fmt = sign_extend(get_le16(pb), 16);
> >> >
> >> > a simple cast to int16_t seems simpler
> >> 
> >> Strictly speaking, that is undefined, but I don't think we care,
> >
> > Could you explain why is this undefined?  My initial guess was that
> > you're not guaranteed that signed integers two's complement,
> 
> Correct.
> 
> > but I thought you were guaranteed that for the fixed-width C99 int
> > types.
> 
> No, you're not.  There are requirements on the range of values they
> can hold, but no requirements on implementation.
> 

>From the copy of C99 TC2 I have:

1.18.1.1 Exact-width integer types

The typedef name intN_t designates a signed integer type with width N ,
no padding bits, and a two?s complement representation. Thus, int8_t
denotes a signed integer type with a width of exactly 8 bits.


-- 
Bobby Bingham
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