[FFmpeg-devel] [RFC/PATCH 6/8] tidsp: add mp4v configuration

[Reimar Döffinger]

On Wed, Sep 08, 2010 at 02:01:26AM +0300, Felipe Contreras wrote:
> On Tue, Sep 7, 2010 at 10:54 PM, Reimar D?ffinger
> <Reimar.Doeffinger at gmx.de> wrote:
> > On Tue, Sep 07, 2010 at 10:26:05PM +0300, Felipe Contreras wrote:
> >> On Tue, Sep 7, 2010 at 10:15 PM, Reimar D?ffinger
> >> <Reimar.Doeffinger at gmx.de> wrote:
> >> > On Tue, Sep 07, 2010 at 12:44:12PM +0300, Felipe Contreras wrote:
> >> >> On Tue, Sep 7, 2010 at 5:45 AM, Ronald S. Bultje <rsbultje at gmail.com> wrote:
> >> >> > On Sun, Sep 5, 2010 at 6:15 PM, Felipe Contreras
> >> >> > <felipe.contreras at gmail.com> wrote:
> >> >> >> +struct mp4vdec_args {
> >> >> >> + ? ? ? uint32_t size;
> >> >> >> + ? ? ? uint16_t num_streams;
> >> >> >> +
> >> >> >> + ? ? ? uint16_t in_id;
> >> >> >> + ? ? ? uint16_t in_type;
> >> >> >> + ? ? ? uint16_t in_count;
> >> >> >> +
> >> >> >> + ? ? ? uint16_t out_id;
> >> >> >> + ? ? ? uint16_t out_type;
> >> >> >> + ? ? ? uint16_t out_count;
> >> >> >> +
> >> >> >> + ? ? ? uint16_t reserved;
> >> >> >> +
> >> >> >> + ? ? ? uint32_t max_width;
> >> >> >> + ? ? ? uint32_t max_height;
> >> >> >> + ? ? ? uint32_t color_format;
> >> >> >> + ? ? ? uint32_t max_framerate;
> >> >> >> + ? ? ? uint32_t max_bitrate;
> >> >> >> + ? ? ? uint32_t endianness;
> >> >> >> + ? ? ? uint32_t profile;
> >> >> >> + ? ? ? int32_t max_level;
> >> >> >> + ? ? ? uint32_t mode;
> >> >> >> + ? ? ? int32_t preroll;
> >> >> >> + ? ? ? uint32_t display_width;
> >> >> >> +};
> >> >> >
> >> >> > What are all these?
> >> >>
> >> >> These are arguments needed to start the DSP algorithm.
> >> >
> >> > Assuming you mean they are directly pass to hardware:
> >> > I don't think a struct is a good way to do this,
> >> > you're relying on the compiler not inserting some
> >> > padding just because it likes to (e.g. on a machine
> >> > that can only do 32 bit read and writes it might allocate
> >> > 4 bytes for all the uint16_t - I admit I haven't double-
> >> > checked this is indeed allowed).
> >>
> >> You mean padding at the end, or in the middle? Appending stuff at the
> >> end is generally not a problem (although some algos check the size
> >> specified). If it's in the middle... how do you suggest fixing that?
> >
> > Building the memory layout manually using bytestream_put_...(),
> > using comments to describe what's written where (since there's
> > no more variable names to guess it from anymore).
> 
> But the code in the 'tidsp' apparently wouldn't belong to FFmpeg, so
> the bytestream_* utilities are not available.

It's not any complex code, since it doesn't have to be efficient it can
be reimplemented in a few minutes...