[FFmpeg-devel] [PATCH v3 3/3] avcodec/hevc: Add alpha layer support

[Zhao Zhili]

> On Feb 5, 2025, at 23:33, James Almer <jamrial at gmail.com> wrote:
> 
> On 2/5/2025 12:10 PM, Zhao Zhili wrote:
>> From: Zhao Zhili <zhilizhao at tencent.com>
>> Signed-off-by: Zhao Zhili <zhilizhao at tencent.com>
>> ---
>>  libavcodec/hevc/hevcdec.c | 72 ++++++++++++++++++++++++++++++++++++++-
>>  libavcodec/hevc/hevcdec.h |  2 ++
>>  libavcodec/hevc/refs.c    | 11 +++++-
>>  3 files changed, 83 insertions(+), 2 deletions(-)
> 
> I tried with https://0x0.st/X7Vx.mov and https://0x0.st/8KCA.mp4, and neither seem to output the alpha plane.

The first sample is a early release from apple, with error in vps extension.

I don’t know where the second sample comes from, it’s blank when playback with QuickTime Player. The bitstream has a lot of error.

Here is a sample encoded with videotoolbox

./ffmpeg -i bunny.mp4 -i basketball.mp4 \
	-filter_complex '[1:v][0:v]alphamerge,format=bgra[vout]’ -\
	c:v hevc_videotoolbox -pix_fmt bgra -alpha_quality 0.5 \
	-t 10 -map '[vout]' -tag:v hvc1 alpha.mp4 

https://drive.google.com/file/d/1SK6gnMNlWODeTySpetNAKgNeqt69DQDz/view?usp=drive_link

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