On 11/28/2024 5:02 PM, Marton Balint wrote:
On Wed, 27 Nov 2024, Marth64 wrote:As it stands today, ffprobe has two stream-level fields (closed_captions and film_grain) that do not work. Their value is always 0 because ffprobe cannot access the internal codec properties in the stream context when it is setting up its internal streams.Additionally, avformat/dump used to successfully print about the presence of Closed Captions (EIA-608/CEA-708) and the presence of film grain. This does not work either anymore, because avformat_find_stream_info() does not copythem in the skeleton context it uses after calling codec_close(). To clarify: the aforementioned features/code are broken.So, to the user, Closed Caption detection as a feature is broken, and ffprobeand the dump is essentially having two fields that do not work. This patchset aims to fix the issue by:(1) Adding a video stream disposition, AV_DISPOSITION_CAPTIONS_EIA608 thatcan be set in avformat_find_stream_info(), and using it to express the presence of Closed Captions (EIA-608/CEA-708)Manually mapping between different codec properties and stream dispositions seems ugly, and I am not sure if we should even use the disposition field for something like this.I suggest you try adding the "properties" attribute to AVCodecParameters, because as far as I see it is very similar to profile or level. Can you see if that works? If it does, we might even promote the FF_CODEC_PROPERTY flags to AV_CODEC_PROPERTY so they will become properly public.
I don't agree it should be in codecpar. It's rarely (if ever) filled during header parsing (codec or container), and instead set when parsing a frame that contains the relevant characteristic that's exported here as a "property", like captions or film grain parameters. Therefore it's not a field used for initialization.
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