On Tue, Jun 19, 2018 at 01:46:27PM +0100, Derek Buitenhuis wrote: > On 19/06/2018 12:31, Michael Niedermayer wrote: > > On Mon, Jun 18, 2018 at 09:19:30PM +0100, Derek Buitenhuis wrote: > >> Just one of the many, many ways to store this stuff in the header. > >> > >> Signed-off-by: Derek Buitenhuis <derek.buitenh...@gmail.com> > >> --- > >> Related reading, but not exactly the same type: > >> * https://github.com/libjpeg-turbo/libjpeg-turbo/issues/92 > >> * > >> https://github.com/libjpeg-turbo/libjpeg-turbo/commit/8ce2c9119a995ef6280f8bba375aac7effb9b571 > >> --- > >> libavcodec/mjpegdec.c | 1 + > >> 1 file changed, 1 insertion(+) > >> > >> diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c > >> index d1dca84d36..e5888ed548 100644 > >> --- a/libavcodec/mjpegdec.c > >> +++ b/libavcodec/mjpegdec.c > >> @@ -568,6 +568,7 @@ int ff_mjpeg_decode_sof(MJpegDecodeContext *s) > >> } > >> break; > >> case 0x21111100: > >> + case 0x41212100: > >> if (s->component_id[0] == 'Q' && s->component_id[1] == 'F' && > >> s->component_id[2] == 'A') { > >> if (s->bits <= 8) s->avctx->pix_fmt = AV_PIX_FMT_GBRP; > >> else > > > > either this is wrong or > > " > > - /* NOTE we do not allocate pictures large enough for the possible > > - * padding of h/v_count being 4 */ > > " > > this is outdated in some way. > > I don't think this was ever a valid comment, since h_coutn and v_count are > not supposed to be interpreted as absolute values to be applied? That is, > you need to look at the ratio.
The absolute values define the bitstream and have to be used > > Further, I am not quite sure what 'padding' refers to in this specific > instance, > since this has to do with subsampling? I'm maybe missing something > JPEG-specific? with a count of 4, mjpeg is coded in MCUs of 4 8x8 blocks in that direction all buffers must be sized accordingly so that these blocks fit in. I suspect that is already done but i could be wrong [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB No snowflake in an avalanche ever feels responsible. -- Voltaire
signature.asc
Description: PGP signature
_______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
