[FFmpeg-devel] [PATCH 1/4] avcodec/frame: add AV_FRAME_FLAG_LOSSLESS

[Marton Balint]

On Mon, 23 Dec 2024, Marton Balint wrote:

>
>
> On Mon, 16 Dec 2024, Marton Balint wrote:
>
>> 
>>
>>  On Mon, 16 Dec 2024, Anton Khirnov wrote:
>>
>>>   Quoting Marton Balint (2024-12-16 09:47:39)
>>>> 
>>>>
>>>>   On Mon, 16 Dec 2024, Anton Khirnov wrote:
>>>>
>>>>>   Quoting Marton Balint (2024-12-15 01:02:42)
>>>>>>   Signed-off-by: Marton Balint <cus at passwd.hu>
>>>>>>   ---
>>>>>>    doc/APIchanges       | 3 +++
>>>>>>    libavcodec/version.h | 2 +-
>>>>>>    libavutil/frame.h    | 4 ++++
>>>>>>    3 files changed, 8 insertions(+), 1 deletion(-)
>>>>>>
>>>>>>   diff --git a/doc/APIchanges b/doc/APIchanges
>>>>>>   index 3a75b803a9..bfba0946d3 100644
>>>>>>   --- a/doc/APIchanges
>>>>>>   +++ b/doc/APIchanges
>>>>>>   @@ -2,6 +2,9 @@ The last version increases of all libraries were on
>>>>>>   2024-03-07
>>>>>>
>>>>>>    API changes, most recent first:
>>>>>>
>>>>>>   +2024-12-xx - xxxxxxxxxx - lavc 61.27.100 - frame.h
>>>>>>   +  Add AV_FRAME_FLAG_LOSSLESS.
>>>>>
>>>>>   I feel ambivalent about this. This is really a decoder property, and
>>>>>   attaching it to frames allows it propagate far away to places where it
>>>>>   makes no sense (the same holds for other existing AVFrame fields, but
>>>>>   I'd prefer for them to be removed).
>>>>
>>>>   The way this flag is set in patch 2 in the series kind of shows why
>>>>   this
>>>>   is a per-frame property, directly originated from the bitstream of
>>>>   codecs
>>>>   supporting both lossy and lossless encoding. The encoder for such
>>>>   codecs
>>>>   is allowed to decide on a frame-by-frame basis if it will use lossy or
>>>>   lossless encoding.
>>>
>>>   I realize this can change per-frame, my point is that it's a per-frame
>>>   property of the decoding process, not of the decoded frame itself.
>>
>>  As you said yourself, we have similar fields already in AVFrame (keyframe,
>>  pict_type, decoder_error_flags). I guess we could return those in a struct
>>  alongside with AVFrame when decoding, but that would complicate stuff in a
>>  lot of places having to deal with two structs, so I am not sure that it's
>>  worth doing just for the somewhat "cleaner" AVFrame...
>
> Ping. So how should we resolve this? Actually the whole point of introducing 
> it was to not lose a "feature" when deprecating the 
> AVCodecContext->properties in patch 4...

Will apply the patchset in 2-3 days.

Regards,
Marton