On 25/03/2024 07:35, Xiang, Haihao wrote:
On Di, 2024-03-19 at 22:52 +0000, Mark Thompson wrote:
On 19/03/2024 04:16, Xiang, Haihao wrote:
On Ma, 2024-03-18 at 21:33 +0000, Mark Thompson wrote:
On 18/03/2024 05:53, Xiang, Haihao wrote:
On So, 2024-03-17 at 20:51 +0000, Mark Thompson wrote:
For hardware cases where we are forced to have a fixed pool of frames
allocated up-front (such as array textures on decoder output), suggest
a possible workaround to the user if an allocation fails because the
pool is exhausted.
---
Perhaps helpful; any thoughts?
The warning comes out before any errors, looking like:
[mpeg2video @ 0x560ff51b4600] Failed to allocate a vaapi/nv12 frame
from a
fixed pool of hardware frames.
[mpeg2video @ 0x560ff51b4600] Consider setting extra_hw_frames to a
larger
value (currently set to 8, giving a pool size of 14).
[mpeg2video @ 0x560ff51b4600] get_buffer() failed
[vist#0:0/mpeg2video @ 0x560ff5199840] [dec:mpeg2video @
0x560ff51b3b40]
Error
submitting packet to decoder: Operation not permitted
I'm OK to print such warning so user may know how to work around it. But
now
many cases are impacted by this error
(e.g. https://trac.ffmpeg.org/ticket/10856
), I think it is a regression to user. I still prefer to use a dynamic
buffer
pool instead fixed frame pool to avoid such error when the dynamic
buffer
pool
can work.
How would we implement this on D3D11 or D3D12?
I understand not all can support dynamic frame pool, your patch is useful
for
decoders using fixed pool. But for driver which doesn't require array
textures,
I think we'd be better to use dynamic frame pool instead so user needn't
worry
about frame allocation. For example, we may use dynamic frame pool for vaapi
with iHD driver, what do you think about adding a quirk to enable dynamic
frame
pool for special drivers ?
I think we should come to a conclusion on what the generic code for this case
should be and then consider whether any special cases are needed.
When compared to the state right now, I agree with you that just switching
VAAPI to always be dynamic would probably be better just to avoid the nasty
failures, but given that we need to improve the situation for cases (like
D3D11) where we don't have an ad-hoc workaround we should be comparing to
whatever that concludes rather than the broken state right now.
Hi Mark,
I agree with you. Will you push this patch ? We may switch to dynamic frame pool
for vaapi cases later after pushing your patch.
Ok, pushed.
Thoughts:
* Passthrough filter chains can have the two queues worth of frames stored
(when e.g. only editing metadata).
* Possibly fixable by just doubling the extra frames added? That seems very
clumsy.
* Filters have no idea how big to make a pool when it is fixed.
* lavfi would need negotiation backwards through the whole graph to make this
work.
* Encoders have no way to signal that they want to hold on to more frames.
* New API needed?
* Without negotiation in lavfi it would be hard to work out in ffmpeg /which/
pool to increase the size of in the presence of nontrivial filter graphs,
though.
* V4L2 M2M decode does not use hwcontext, but suffers from the same problems
with a fixed pool.
* Not updated since e0da916, probably broken by it in some cases. (Does warn with the
ad-hoc workaround option "num_capture_buffers".)
* Does anyone ever use this in the ffmpeg utility?
Thanks,
- Mark
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