[FFmpeg-devel] [PATCH v3 1/2] lavf/isom: support for demuxing MPEG-H 3D Audio in MP4

[Tsuchiya, Yuki (SHES)]

Hi Jan,

Thank you for the comment.

> All of the samples I've seen in the wild (well, on the DASH-IF test
> vector list, which is the only place I've seen both AC-4 and MPEG-H
> Audio at until now) seem to utilize mha1, such as
> https://dash.akamaized.net/dash264/TestCasesMCA/fraunhofer/MPEGH_714_lc_mha1/1/Sintel/Sintel.2010_1080p_incl_Credits_new_cicp19_16bit-eng-893s-12-mpegh-256000bps_seg.mp4
> Thus my initial question is if there is any reason why 'mha1' is not
> added as well? Was that removed from the MP4 container specification
> afterwards?
'mha1' is still documented on ISO, but the latest DASH-IOP specifies to use only mhm1 (https://dashif.org/docs/DASH-IF-IOP-v4.3.pdf) from v4.3.
So it seems likely that mhm1 will become majority in MPEG-H 3D Audio in MP4. This is why this patch supports mhm1 as priority.

> Additionally, are there any MPEG-H Audio specific
> configuration/etc boxes required to be read/written for valid decoding
> or to create a valid mux according to the spec which should be
> handled?
In mha1 case, it is required to handle 'mhaC' box which contains configuration for decoding. 
In mhm1 case (this patch), MHAS bitstream in mdat has the configuration, so the 'mhaC' is not required to handle.

Regards.

Yuki Tsuchiya