[FFmpeg-user] Amerge trouble

[Bouke / VideoToolShed]

On 18 Nov 2017, at 17:24, Erik Dobberkau <erik.dobberkau at gmail.com> wrote:
> 
> or if you want a single audio stream with 5 channels:
> 
> ffmpeg -i HD422.mxf -i 8ch.wav -c:v copy -c:a pcm_s24le -filter_complex \
> "[1:a]channelsplit=channel_layout=7.1[a0][a1][a2][a3][a4][a5][a6][a7],\
> [a1][0:a:1][a0][0:a:0][0:a:2]amerge=inputs=5[a]" \
> -map 0:v -map "[a]" -timecode 01:00:00:00 testmerge01.mxf \
> -map "[a2]" -map "[a3]" -map "[a4]" -map "[a5]" -map "[a6]" -map "[a7]" -f
> null -

Hi Eric,
Great (I would never have come up with the way of disposing unwanted channels.)
One problem though, It seems that FFmpeg pipes the channel split, but does so in 16 bits:

  Stream #1:0: Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, 7.1, s32 (24 bit), 9216 kb/s
Stream mapping:
  Stream #0:1 (pcm_s24le) -> amerge:in3
  Stream #0:2 (pcm_s24le) -> amerge:in1
  Stream #0:3 (pcm_s24le) -> amerge:in4
  Stream #1:0 (pcm_s24le) -> channelsplit
  Stream #0:0 -> #0:0 (copy)
  amerge -> Stream #0:1 (pcm_s24le)
  channelsplit:FC -> Stream #1:0 (pcm_s16le)
  channelsplit:LFE -> Stream #1:1 (pcm_s16le)
  channelsplit:BL -> Stream #1:2 (pcm_s16le)
  channelsplit:BR -> Stream #1:3 (pcm_s16le)
  channelsplit:SL -> Stream #1:4 (pcm_s16le)
  channelsplit:SR -> Stream #1:5 (pcm_s16le)

And after that promote it to 24 bits again.
Is there a way to force the channel split to work in 24 bits?
(No idea how to squeeze pcm_s24le into the filter_complex part…)

Bouke

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