On Sat, Aug 15, 2020 at 12:29 PM Jan Ekström <jee...@gmail.com> wrote: > > On Fri, Aug 14, 2020 at 8:36 PM Michael Niedermayer > <mich...@niedermayer.cc> wrote: > > > > On Thu, Aug 13, 2020 at 01:26:58AM +0300, Jan Ekström wrote: > > > This is as far as 22.2 follows the same channel order as > > > WaveFormatExtensible's channel mask (and the AV_CH_* defines). > > > > > > After LFE2 the side channels would follow, but that offset of > > > one stops us from utilizing them without further tweaks. > > > > > > This change was verified by using swresample to downmix to 5.1, > > > and then feeding that to WASAPI. > > > --- > > > libswresample/rematrix.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > probably ok > > > > Thanks for taking a look. I originally planned on sending a link to a > test sample I created somewhere during the time attempting to validate > the AAC decoder, which I then also utilized to check the result of > this: > https://megumin.fushizen.eu/samples/22.2_input_test_sample.wav > > ...but alas then I never got to it afterwards. >
Aand once again hit the send button a bit too soon. For context, the reason why I started poking at this a bit more is because a friendly person elsewhere who implemented 22.2 to X downmix on his side pointed out that https://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-BS.2159-8-2019-PDF-E.pdf contained the downmix matrix to 5.1 (TABLE11, System H is 22.2). So I planned on taking the same shortcut of doing 22.2->5.1->X, since 5.1 was already implemented or could be pushed to most audio output systems, but after looking at rematrix for a bit I got that no such shortcuts would be possible. So now the plan is to attempt to see if: 1) I can work around the +1 offset for side left/right, thus creating the base level 10.1 that seems to be implemented in rematrix. 2) Mix top/bottom channels into their matching base level, adding support for them being mixed in. 3) Mix LFE2 into LFE1. If this would work, we could get a downmix going by means of 22.2->10.1->X . Jan _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".