On Sat, 1 Jan 2022, Pierre-Anthony Lemieux wrote:
On Sat, Jan 1, 2022 at 5:11 PM Marton Balint <c...@passwd.hu> wrote:
On Sat, 1 Jan 2022, Pierre-Anthony Lemieux wrote:
Minor suggestion below.
In addition, will sample file(s) be added to FATE? Below are two examples:
http://ffmpeg-imf-samples-public.s3.us-west-1.amazonaws.com/callout_51_l_r_c_lfe_ls_rs.mxf
http://ffmpeg-imf-samples-public.s3.us-west-1.amazonaws.com/callout_51_l_c_r_ls_rs_lfe.mxf
Good idea, can someone with access please upload these to the fate mxf
folder?
[...]
I suggest adding the following audio channels, which are specified in
SMPTE ST 2067-8 [1] and have a direct mapping to ffmpeg audio
channels:AV_CH_STEREO_LEFT
urn:smpte:ul:060e2b34.0401010d.03020120.03000000 (Left Total) ->
AV_CH_STEREO_LEFT
urn:smpte:ul:060e2b34.0401010d.03020120.04000000 (RightTotal) ->
AV_CH_STEREO_RIGHT
[1] https://registry.smpte-ra.org/view/published/labels_view.html
Unfortunately this is a Dolby encoded stereo mix, not an ordinary LeftOnly
/ RightOnly mix. So I am not how this should be signalled.
My interpretation below.
In "mov_chan.c", AV_CH_LAYOUT_STEREO_DOWNMIX means
MOV_CH_LAYOUT_MATRIXSTEREO [1], which is defined in Core Audio [2].
LtRt, i.e. matrix-encoded audio, is not generally Dolby-specific [3].
[1]
https://github.com/FFmpeg/FFmpeg/blob/d6b2357eddca392ee137cb2a92ff178a0a7d0cce/libavformat/mov_chan.c#L168
[2]
https://developer.apple.com/documentation/coreaudiotypes/1572101-audio_channel_layout_tags/kaudiochannellayouttag_matrixstereo?changes=_8_7&language=objc
[3] https://en.wikipedia.org/wiki/Matrix_decoder
Well, ok, I will add these two labels then before pushing.
Thanks,
Marton
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