Re: [gst-devel] qtdemux nal slice size

[vineeth <nvi...@gm...>]

Hi ,
  Thanks for the kind reply,
  I could more info from class AVCDecoderConfigurationRecord of 14496-part
15, thanks to your pointers.

--vineeth


On Sun, Sep 12, 2010 at 5:38 PM, Sandeep Prakash <123...@gm...> wrote:

>
> Hi Vineeth,
>
>
> vineeth wrote:
> >
> >   For few mp4 files, the first 4 bytes correspond to NumBytesInNalUnit
> and
> > for few other the first 2 bytes tell the Nal Unit size. Is there a way to
> > determine if the first 4 or the first 2 bytes give the size on Nal unit?
> >
> In case of h264 streams qtdemux will give the decoder config info in the
> caps as
> "codec_data", as a GstBuffer. Note that this is not the bytestream format.
> This comprises of:
> <6 bytes avcC atom> + <SPS> + <1 byte indicating Number of PPS present> +
> <PPS> + <PPS> + ....
>
> In the avcC atom the 2 Least Significant Bits of the 5th Byte corresponds
> to
> the
> (NumBytesInNalUnit -1). So to get the NumBytesInNalUnit (Length of Length
> of
> NAL):
> length_of_length = (<5th Byte of "codec_data"> & 0x3) + 1
>
>
> vineeth wrote:
> >
> >   Also, is it possible to configure qtdemux to give Nal units with NAL
> > prefix ( Annex-B of *14496-10* standard)
> >
> AFAIK configuration is not possible.
>
>
> Regards,
> Sandeep Prakash
> http://sandeepprakash.homeip.net
>
> --
> View this message in context:
> http://gstreamer-devel.966125.n4.nabble.com/qtdemux-nal-slice-size-tp2535442p2536285.html
> Sent from the GStreamer-devel mailing list archive at Nabble.com.
>
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