Should h264parse limit the max PPS id to 31 or 255?

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Should h264parse limit the max PPS id to 31 or 255?

Karen Schoener
Hi, 

I notice that the h264parse element currently limits the max PPS id to 31.

According to section 7.4.2.2 in the H264 spec, the PPS id may range from 0-255.  However the SPS id can range from 0-31.

Here's the info from 7.4.2.2 in the H264 spec:
pic_parameter_set_id identifies the picture parameter set that is referred to in the slice header. The value of pic_parameter_set_id shall be in the range of 0 to 255, inclusive.

seq_parameter_set_id refers to the active sequence parameter set. The value of seq_parameter_set_id shall be in the range of 0 to 31, inclusive.

I was just wondering if this PPS ID limit to 31 was intentional.

Does anyone see an issue with changing the following #define in h264parse.h from 32 to 256?
#define MAX_PPS_COUNT   32

Thanks, Karen

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Re: Should h264parse limit the max PPS id to 31 or 255?

Loren Rogers
Hi Karen,
The h.264 spec definitely specifies 8 bits (0-255).  I've had
experience with some devices/codecs populating the PPS ID to something
definitely greater than 31.  It does seem incorrect to me also.  Maybe
adjust the h264parse.h to reflect that specific device/codec?  But a
response from the gstreamer folks would be most helpful.
Thanks
/Loren


On Mon, May 2, 2011 at 3:12 PM, Karen Schoener <[hidden email]> wrote:

> Hi,
> I notice that the h264parse element currently limits the max PPS id to 31.
> According to section 7.4.2.2 in the H264 spec, the PPS id may range from
> 0-255.  However the SPS id can range from 0-31.
> Here's the info from 7.4.2.2 in the H264 spec:
>
> pic_parameter_set_id identifies the picture parameter set that is referred
> to in the slice header. The value of pic_parameter_set_id shall be in the
> range of 0 to 255, inclusive.
> seq_parameter_set_id refers to the active sequence parameter set. The value
> of seq_parameter_set_id shall be in the range of 0 to 31, inclusive.
>
> I was just wondering if this PPS ID limit to 31 was intentional.
> Does anyone see an issue with changing the following #define in h264parse.h
> from 32 to 256?
>
> #define MAX_PPS_COUNT   32
>
> Thanks, Karen
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>
>



--
"Some men see things as they are and say why. I dream things that
never were and say why not?" - GBS
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