[FFmpeg-devel] [PATCH] avcodec: uninit hwaccel in case of software decoder

[Thomas Guillem]

Hi,

On Tue, Dec 10, 2024, at 19:29, Anton Khirnov wrote:
> Hi,
> Quoting Thomas Guillem via ffmpeg-devel (2024-11-29 11:44:21)
>> avcodec_get_hw_frames_parameters(), called by the user from get_format,
>> is allocating ctx->internal->hwaccel_priv_data. But the hardware
>> decoding setup may fail on the user side and it may fallback to software
>> decoding. In that case, ctx->internal->hwaccel_priv_data is still
>> allocated but not used anymore.
>> 
>> Fixes the following assert:
>> 
>> Assertion p_dst->hwaccel_threadsafe || (!dst->hwaccel && !dst->internal->hwaccel_priv_data) failed at src/libavcodec/pthread_frame.c:426
>> ---
>>  libavcodec/decode.c | 2 ++
>>  1 file changed, 2 insertions(+)
>
> I think the actual problem is that avcodec_get_hw_frames_parameters()
> modifies the codec context, even though it's explicitly documented not
> to. I discussed this with Lynne on IRC, and she's working on removing
> the need for that from vulkan decoding, which should be a more proper
> fix here.

Indeed, it seems to be a proper solution.

Note that 6.x and 7.1 will need a backport of the fix (or a workaround like this patch if it is too complex to backport).

>
> -- 
> Anton Khirnov
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