Hi guys,
Users of our software reported that certain H.264 files show green lines in the
middle of the image.
Here’s the output of av_dump_format:
Metadata:
major_brand : qt
minor_version : 537199360
compatible_brands: qt
creation_time : 2017-05-23T06:14:36.000000Z
timecode : 00:59:52:00
Duration: 00:43:19.64, start: 0.000000, bitrate: 1838 kb/s
Stream #0:0(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo,
fltp, 250 kb/s (default)
Metadata:
creation_time : 2017-05-23T06:14:37.000000Z
handler_name : Apple Alias Data Handler
Stream #0:1(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv,
smpte170m/smpte170m/bt709), 720x405, 1578 kb/s, 23.98 fps, 23.98 tbr, 23976
tbn, 47.95 tbc (default)
Metadata:
creation_time : 2017-05-23T06:14:37.000000Z
handler_name : Apple Alias Data Handler
encoder : H.264
Stream #0:2(eng): Data: none (tmcd / 0x64636D74) (default)
Metadata:
creation_time : 2017-05-23T06:48:54.000000Z
handler_name : Apple Alias Data Handler
timecode : 00:59:52:00
I uploaded a screenshot of how the bug looks here:
https://www.dropbox.com/s/49ri0traypnyhzd/Decoding_ShiftedPlanes.png?dl=0
<https://www.dropbox.com/s/49ri0traypnyhzd/Decoding_ShiftedPlanes.png?dl=0>
The same files work fine in QuickTime and VLC (and also in an older version of
our software using swscale instead of our own GPU pixel format converter).
By further evaluating the issue it turns out that the V plane contained in the
AVFrame’s->data[2] field apparently doesn’t contain straight V values but
something different.
We’re decoding the frames using avcodec_decode_video2. If the output is
converted using swscale, everything looks good.
If we only use av_picture_layout, the issue looks like in the screenshot.
The only difference I can spot to other H.264 files looking correct is the
“smpte170m/smpte170m/bt709” color space tags where others have only one (bt709).
Does anyone have an explanation for that or can give me some more insight on
where to look at?
Any hints are greatly appreciated!
Thanks and best,
Flo
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