#11630: Regression: hevcdec with videotoolbox hwaccel aborts on broken frames
after
commit 79afc45c03abfb7f1d9dc2cc758ec162bfade1a0
-------------------------------------+-------------------------------------
Reporter: gnattu | Type: defect
Status: new | Priority: normal
Component: avcodec | Version: git-
Keywords: | master
videotoolbox hevc | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
Summary of the bug:
Since commit `79afc45c03abfb7f1d9dc2cc758ec162bfade1a0` (lavc/hevcdec: use
a ContainerFifo to hold frames scheduled for output), the behavior of the
HEVC decoder (`hevcdec`) with videotoolbox hardware acceleration has
changed. When decoding input files that contain broken frames, the decoder
now aborts early instead of continuing to decode subsequent good frames,
as it did before.
This is verified by bisecting from 7.0.2 to 7.1.1:
{{{
79afc45c03abfb7f1d9dc2cc758ec162bfade1a0 is the first bad commit
commit 79afc45c03abfb7f1d9dc2cc758ec162bfade1a0
Author: Anton Khirnov <an...@khirnov.net>
Date: Thu Jun 20 21:01:49 2024 +0200
lavc/hevcdec: use a ContainerFifo to hold frames scheduled for output
Instead of a single AVFrame.
Will be useful in future commits, where we will want to produce
multiple
output frames for a single coded frame.
libavcodec/Makefile | 2 +-
libavcodec/hevc/hevcdec.c | 31 +++++++++++++++++++++----------
libavcodec/hevc/hevcdec.h | 4 ++--
libavcodec/hevc/refs.c | 12 ++++--------
4 files changed, 28 insertions(+), 21 deletions(-)
}}}
How to reproduce:
1. Download this sample, which contains broken frames at the beginning:
https://drive.usercontent.google.com/download?id=1z5dRzJ1PMSTphUqXa379Ourm1OdARIO_&export=download&authuser=0
2. Run the following command:
{{{
./ffmpeg -hide_banner -hwaccel videotoolbox -hwaccel_output_format
videotoolbox_vld -i './LG Cymatic Jazz 4K Demo.ts' -vcodec
h264_videotoolbox -an -sn -dn test.mp4
}}}
You should observe the bug, where decoding aborts after encountering
broken frames instead of continuing:
{{{
[hevc @ 0x142e1e860] No frame decoded?
[vist#0:0/hevc @ 0x144004b90] [dec:hevc @ 0x142e17820] Error submitting
packet to decoder: Generic error in an external library
[vist#0:0/hevc @ 0x144004b90] [dec:hevc @ 0x142e17820] Error submitting
packet to decoder: Unknown error occurred
[vist#0:0/hevc @ 0x144004b90] [dec:hevc @ 0x142e17820] A decoder returned
an unexpected error code. This is a bug, please report it.
[vist#0:0/hevc @ 0x144004b90] [dec:hevc @ 0x142e17820] Error processing
packet in decoder: Internal bug, should not have happened
[vist#0:0/hevc @ 0x144004b90] [dec:hevc @ 0x142e17820] Task finished with
error code: -558323010 (Internal bug, should not have happened)
[vist#0:0/hevc @ 0x144004b90] [dec:hevc @ 0x142e17820] Terminating thread
with return code -558323010 (Internal bug, should not have happened)
}}}
In 7.0.2, it will continue decoding past the broken frames, despite the
log is also flooded with decode errors:
{{{
[hevc @ 0x150e1efa0] Could not find ref with POC 38
[hevc @ 0x150e175b0] vt decoder cb: output image buffer is null: -17694
[hevc @ 0x150e1efa0] hardware accelerator failed to decode picture
[vist#0:0/hevc @ 0x150e08d30] [dec:hevc @ 0x150e16020] Error submitting
packet to decoder: Unknown error occurred
Last message repeated 7 times
}}}
A temporary workaround is to change line 127 of `videotoolbox.c` to not
return `AVERROR_EXTERNAL` if no frame was decoded, but to return 0 after
unreffing the frame. This allows decoding to continue with invalid frame
warning:
{{{
[hevc @ 0x11a604f40] An invalid frame was output by a decoder. This is a
bug, please report it.
}}}
But this is probably not the best way to restore the old behavior, and
therefore I created this ticket.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/11630>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker
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