[FFmpeg-devel] Add support for LJ92 compressed MLV files

South East 8billion.people at gmail.com
Wed Oct 23 20:50:46 EEST 2024


Thanks.  I tried to run Fate tests locally, but they were broken for me,
before and after my changes, with the same error (not the error you're
reporting, something about fate-ffmpeg-spec-disposition).

Is this something I need to look into?  I don't have a tests/data dir (I
assume you don't want to store a bunch of large files in git).  How would I
reproduce this test failure?

My changes are small in scope.  I don't have much knowledge of ffmpeg,
nothing feels like to cause problems.  I guess the most likely would be
settings s->bayer = 1, earlier than before.  But that only happens when
we're confident the pix_fmt is Bayer.

On Wed, 23 Oct 2024 at 15:56, Michael Niedermayer <michael at niedermayer.cc>
wrote:

> On Mon, Oct 21, 2024 at 07:44:47PM +0100, South East wrote:
> > ffmpeg has existing support for MLV raw video files;
> libavformat/mlvdec.c.
> > Since this was added, MLV has been extended to support LJ92 compressed
> > image data.  These patches build on lossless DNG support in 7.2-dev to
> > enable handling LJ92 MLV via existing libavcodec/mjpegdec.c code.
> >
> > I can provide MLV sample files if desired, being raw video these tend to
> be
> > large.
> >
> > Thanks to JEEB and Lynne for help via IRC.
>
> [...]
>
> >  mjpegdec.c |   15 +++++++++------
> >  1 file changed, 9 insertions(+), 6 deletions(-)
> > 1a3179f82c90802bb70079da08623769207f7e2a
> 0001-avcodec-mjpegdec-set-bayer-flag-based-on-pix_fmt.patch
> > From bda19449cce6ae028ef751f0f4f21da63214ab3f Mon Sep 17 00:00:00 2001
> > From: stephen-e <33672591+reticulatedpines at users.noreply.github.com>
> > Date: Mon, 21 Oct 2024 16:32:01 +0100
> > Subject: [PATCH 1/2] avcodec/mjpegdec: set bayer flag based on pix_fmt
> >
> > dng_decode_jpeg() does this directly in tiff.c,
> > this change allows signalling via the pixel format
> > (to support LJ92 compressed raw video in MLV containers,
> > which is the next commit).
> > ---
> >  libavcodec/mjpegdec.c | 15 +++++++++------
> >  1 file changed, 9 insertions(+), 6 deletions(-)
>
> breaks
>
> fate-vsynth1-amv
>
> --- ./tests/ref/vsynth/vsynth1-amv      2024-10-14 18:05:24.547329331 +0200
> +++ tests/data/fate/vsynth1-amv 2024-10-23 16:51:21.188674970 +0200
> @@ -1,4 +1,2 @@
>  9e155fcedb3b853876e9ea4233971803 *tests/data/fate/vsynth1-amv.avi
>  1365500 tests/data/fate/vsynth1-amv.avi
> -e38681b9527b6d2531942f8a176a0265 *tests/data/fate/vsynth1-amv.out.rawvideo
> -stddev:   10.07 PSNR: 28.06 MAXDIFF:   98 bytes:  7603200/  7603200
> Test vsynth1-amv failed. Look at tests/data/fate/vsynth1-amv.err for
> details.
> make: *** [tests/Makefile:311: fate-vsynth1-amv] Error 69
>
> thx
>
> [...]
>
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Everything should be made as simple as possible, but not simpler.
> -- Albert Einstein
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