[XviD-devel] illegal MPEG-4 Bitstream Syntax / RAW YUV input swaped

[Jim Hauxwell]

Hi,

I'm doing the same as you with YUV and I have not found a problem with the
chroma channels getting swapped.  What platform are you on?

Jim

> -----Original Message-----
> From: xvid-devel-admin@xvid.org [mailto:xvid-devel-admin@xvid.org]On
> Behalf Of Andreas Dehnhardt
> Sent: 03 January 2003 21:35
> To: xvid-devel@xvid.org
> Subject: [XviD-devel] illegal MPEG-4 Bitstream Syntax / RAW YUV input
> swaped
>
>
> Hi everyone,
>
> 1) illegal MPEG-4 Bitstream Syntax
>
> I was playing around with the xvidcore-0.9.0 codec and found out
> the following:
> After encoding a sequence to a raw MPEG-4 bitstream, I tried to decode
> it using the standard MPEG-4 decoder (the reference ISO fpdam decoder).
>
> The decoding failed at the second I-VOP, it complained about an illegal
> VOP_START_CODE while parsing the bitstream. This error is caused by
> FrameCodeI() in "encoder.c". There is a new VO/VOL-Header
> inserted into the
> bitstream (BitstreamWriteVolHeader()) for every new I-VOP. According to
> the MPEG-4 standard, this structure is illegal. The VO/VOL-Header is only
> allowed at the start of the sequence. The VOPs (in our case, a Frame is
> equal to a VOP) are instances of one VideoObject (VO) at a given time.
> VideoObjectLayers (VOLs) are used for object based temporal and spatial
> scalability (not included in the simple profile of MPEG-4). We only have
> one VO and one VOL, so we cannot include more than one VO/VOL-Header.
>
> I disabled the BitstreamWriteVolHeader()-call (except for the
> initial I-VOP).
> After this modification, the standard MPEG-4 decoder was able to decode
> the whole bitstream.
>
> Did anyone play around with decoding the raw MPEG-4 stream using other
> decoders before?
>
>
>
>
> 2) RAW YUV input swaped
>
> I used raw YUV data as input for the encoder. After encoding (xvid_encraw)
> and decoding (fpdam), the colors seem to be somehow "wrong". I swaped
> the order of U and V in my input YUV-file. This fixed the error. I don't
> know the "correct" order of a YUV-file. Either the encoder swaps the
> color information while reading the raw data or there is no standard
> YUV-order for such files???
>
>
>
>
> I hope this is useful for anyone and we will have a nice
> discussion about VO/VOL/VOP :-)
>
>
> Have fun,
> Andreas
>
>
> _______________________________________________
> XviD-devel mailing list
> XviD-devel@xvid.org
> http://list.xvid.org/mailman/listinfo/xvid-devel