Re: [FFmpeg-devel] [PATCH] avutil/avframe: fix channel layout checks in av_frame_copy()

[James Almer <jamrial@gmail.com>]

On 5/27/2022 5:12 AM, Tomas Härdin wrote:
> ons 2022-05-25 klockan 14:15 -0300 skrev James Almer:
>> Normally, both the source and dest frame would have only the old API
>> fields
>> set, only the new API fields set, or both set. But in some cases,
>> like when
>> calling av_frame_ref() using a non reference counted source frame
>> where only
>> the old channel layout API fields were populated, the result would be
>> the dst
>> frame having both the new and old fields populated.
>>
>> This commit takes this into account and fixes the checks by calling
>> av_channel_layout_compare() only if the source frame has the new API
>> fields
>> set, and doing sanity checks for the source frame old API fields if
>> the new
>> ones are not set.
> 
> A bit of context for those wondering: this is part of ensuring melt
> works both with FFmpeg 5.0 and the new channel layout API. They're
> still using deprecated things, but one step at a time.

I assume it may be affecting other library users, since it's a matter of 
passing an AVFrame with no reference counted buffers (nothing in buf[], 
only data[] pointers filled) and only the old channel layout API fields 
set to av_frame_ref() or anything that calls it, like avcodec_send_frame().

The amount of users of the new channel layout at this point is probably 
very small, since it's not present in any release. I can't say how many 
users passing AVFrames with non reference counted buffers are out there, 
but it's a supported scenario, so melt may not be the only case.

> 
>>
>> Signed-off-by: James Almer <jamrial@gmail.com>
>> ---
>>   libavutil/frame.c | 19 +++++++++++++++----
>>   1 file changed, 15 insertions(+), 4 deletions(-)
> 
> Works
> 
> /Tomas
> 
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