Oliver Fromme wrote:
> I've got another question about HDR re-encoding.
>
> There are "hybrid" files that contain both Dolby Vision (DoVi) and
> HDR10 (or even HDR10+) metadata at the same time. I don't care about
> the DoVi metadata, so I just remove it. I only encode with the HDR10
> metadata. The resulting files play fine with mpv.
>
> However, when I look at the resulting file (h265 within mkv) with
> ffprobe, it still displays a side_data record for the video stream
> that has the type "DOVI configuration record". Excerpt of ffprobe
> for the video stream (JSON format):
>
> 'streams': [
> {
> [...]
> 'codec_long_name': 'H.265 / HEVC (High Efficiency Video Coding)'
> [...]
> 'side_data_list': [
> {
> 'bl_present_flag': 1
> 'dv_bl_signal_compatibility_id': 1
> 'dv_level': 6
> 'dv_profile': 8
> 'dv_version_major': 1
> 'dv_version_minor': 0
> 'el_present_flag': 0
> 'rpu_present_flag': 1
> 'side_data_type': 'DOVI configuration record'
> }
> ]
> [...]
> }
>
> The video is definitely *not* Dolby Vision, it does not contain any
> BL or RPU data or anything else. Therefore I would like to get rid
> of that "DOVI configuration record" because it might confuse certain
> players.
>
> How to do that?
>
> During my research I noticed that ffmpeg has a multimedia filter
> named "sidedata". It's supposed to be able to delete side data from
> frames. However, the documentation (manual page) refers to the
> AVFrameSideDataType enum in libavutil/frame.h that conatins all
> AV_FRAME_DATA_* values. But that enum does not contain an entry for
> DoVi configuration records. So it must be something else.
Replying to myself ...
I searched the ffmpeg source code up and down, and came to the
conclusion that there is no way to prevent it from copying that
record to the target file.
So I made a quick hack and patched libavformat/matroskaenc.c
where it calls av_packet_side_data_get(..., AV_PKT_DATA_DOVI_CONF).
I simply removed the ``if (!sd)'' line, so it never writes such
data. A better solution would be to make that behaviour configurable
by an option, of course.
It's also worth noting that libx265 offers an option called
"dolby-vision-profile". The default is 0, which means disabled.
This setting can be passed with ffmpeg's -x265-params option.
I guess it would make sense to write the "DOVI configuration record"
*only* if the user specified a non-zero dolby-vision-profile.
Best regards
Oliver
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