APV: Initial support

[cjee21]

Specification and samples: https://github.com/AcademySoftwareFoundation/openapv
More info: https://developer.android.com/about/versions/16/features#apv

Samples in MP4 can be generated with FFmpeg:

ffmpeg -f lavfi -i testsrc=d=10:s=3840x2160:r=60 -pix_fmt yuv422p10le -c:v liboapv -preset slow

or for color_description_present_flag = 1:

ffmpeg -f lavfi -i testsrc=d=10:s=3840x2160:r=60 -pix_fmt yuv422p10le -vf "setparams=color_primaries=bt709:color_trc=bt709:colorspace=bt709" -c:v liboapv -preset slow

[cjee21]

Samples in MP4 from Android CTS: https://dl.google.com/android/xts/cts/tests/media/CtsMediaV2TestCases-5.11.zip

This PR should be enough for showing important info for APV in MP4 that will be produced from 2026 Android phones.

[JeromeMartinez]

I would prefer to have a dedicated source file for APV, similar to AV2, and to put apvC parsing code in it (similar to e.g. hvcC parsing).

[JeromeMartinez]

Generaly speaking, remove the [i] and [i][j] stuff, ad "Element_Begin1("configuration_entry")" and "Element_Begin1("frame_info")" and the corresponding "Element_End0()" instead, for a nicer trace.

[cjee21]

I would prefer to have a dedicated source file for APV, similar to AV2, and to put apvC parsing code in it (similar to e.g. hvcC parsing).

Since it is likely that 2026 Android devices that support APV will use APV in MP4 and the information from apvC seems enough, I did not plan to add a APV parser or parse the raw APV files so I just put it here like some of the other codecs in order to not have to add more files and modify many files.

[cjee21]

I would prefer to have a dedicated source file for APV, similar to AV2, and to put apvC parsing code in it (similar to e.g. hvcC parsing).

Now I split it into separate parser and started adding support for raw bitstreams. Still expanding the parsing.

[cjee21]

@JeromeMartinez parsing can be considered done.

The following remains:

• Filling Y/YUV/RGB. I am not sure about this.
• Handling finishing (right now does not stop parsing). You may be able to do this better.
• Handling case where stream has more than one group/pbu_type with different characteristics. You may have better idea on how to handle as well.
• Using ITU T35 parser (again) to handle the HDR10+ metadata. Right now does not detect HDR10+ in a test sample.

[JeromeMartinez]

Filling Y/YUV/RGB. I am not sure about this.

Could you provide a couple of samples?

Using ITU T35 parser (again) to handle the HDR10+ metadata.

they put it everywhere!
I split the T35 parser soon.

[cjee21]

All samples are from links in post 1 and 2 above. Other samples can be made using FFmpeg which can encode APV.

PS actually AV2 has subsampling position as well but I also do not really know about that so did not fill to prevent filling wrong info.