[FFmpeg-devel] decklink 24/32 bit question

Marton Balint cus at passwd.hu
Wed Oct 18 22:02:57 EEST 2017

On Tue, 17 Oct 2017, Devin Heitmueller wrote:

>> > The decklink sdk only defines two BMDAudioSampleType values: bmdAudioSampleType16bitInteger and bmdAudioSampleType32bitInteger. I don't think there's an easy way to support a 24 bit input here. Generally in this case I've used bmdAudioSampleType32bitInteger and then encode it at pcm_s24le.
>> Dave Rice
> For what it’s worth, I’ve got deinterleaving code in the works to handle 
> capture of multiple pairs of audio (i.e. break 16 channels into 8 pairs 
> and announce them as separate S16LE streams).  If we really thought 
> 24-bit was desirable, that code could be adjusted accordingly (the 
> hardware would still capture 32-bit, but the deinterleaver would put out 
> S24LE).

Breaking 8/16 channels to stereo streams can be done by an audio filter 
(by using "asplit" to multiply the source to 4 outputs and then "pan" or 
"channelmap" on each output to select the proper source channels), so I 
don't think direct support of splitting channels in the decklink device is 

If you have performance or convenience problems with using the 
filters above then propose a filter wich does this in a single step or 
extend one of the existing ones to be able to do this.


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