[FFmpeg-devel] [PATCH] Handle AVID MJPEG streams directly in the MJPEG decoder.

[Michael Niedermayer]

On Wed, Feb 24, 2021 at 11:25:42AM +0100, Anton Khirnov wrote:
> AVID streams - currently handled by the AVRN decoder - can be (depending
> on extradata contents) either MJPEG or raw video. To decode the MJPEG
> variant, the AVRN decoder currently instantiates a MJPEG decoder
> internally and forwards decoded frames to the caller (possibly after
> cropping them).
> 
> This is suboptimal, because the AVRN decoder does not forward all the
> features of the internal MJPEG decoder, such as direct rendering.
> Handling such forwarding in a full and generic manner would be quite
> hard, so it is simpler to just handle those streams in the MJPEG decoder
> directly.
> 
> The AVRN decoder, which now handles only the raw streams, can now be
> marked as supporting direct rendering.
> 
> This also removes the last remaining internal use of the obsolete
> decoding API.
> ---
> And now without the missing isom tag change. Thanks to Andreas for noticing.
> ---
>  configure               |  1 -
>  libavcodec/avrndec.c    | 71 +----------------------------------------
>  libavcodec/mjpegdec.c   | 11 +++++++
>  libavcodec/version.h    |  2 +-
>  libavformat/avidec.c    |  6 ++++
>  libavformat/isom_tags.c |  4 +--
>  tests/fate/video.mak    |  2 +-
>  7 files changed, 22 insertions(+), 75 deletions(-)

breaks:
./ffmpeg -vlowres 2 -i ~/tickets/162/avid.avi  -vframes 3 avrn.avi

The outputed image is several times bigger and looks as if it encodes random bits od memory

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No human being will ever know the Truth, for even if they happen to say it
by chance, they would not even known they had done so. -- Xenophanes
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