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how to extract two of three audiochannels from .mov?
Posted: Mon May 08, 2017 10:27 am
by ThomasM
Hi there,
anyone in here with an understanding with multiple audio-channels in .mov-files?
The Quest:
Convert uncompressed SD-Video 422 10-Bit wit three audio-channels to DVCpro50 with two Audio-Channels (the first two of the three in the original file).
In other words: convert to another video-format and kick audio-channel three.
I tried A/V-Media (Audio only) -> channel mapper (1:1 / 2:2), but this does not work. I always get a stereo-mixdown of all three channels.
What do I do wrong?
Any help appreciated,
regards,
tom
Re: how to extract two of three audiochannels from .mov?
Posted: Mon May 08, 2017 3:55 pm
by admin
Hi ThomasM,
What encoder are you using?
-steinar
Re: how to extract two of three audiochannels from .mov?
Posted: Tue May 09, 2017 12:40 pm
by ThomasM
Hi Steinar,
I tried the preset-encoder DVCpro50 and MP4 / h264. In both cases I get a kind of mixdown.
I used the channel-mapper in stereo-mode. 1-> 1 and 2 -> 2.
thanks for any suggestions,
tom
Re: how to extract two of three audiochannels from .mov?
Posted: Thu May 11, 2017 4:55 pm
by admin
FFFAStrans don't do mixdown of channels. They are always distributed counting from the first channel in the first audio stream. If your source has 3 channels in total they will be mapped to the corresponding output channels count by default, unless you map otherwise in the "Channel Mapper"-filter.
If you're doing 1->1, 2->2 channel mapping and specifying 2x1 (two mono streams) or 1x2 (one stereo stream) in the encoder output it should all be fine. Also, if you have added the "A/V Media"->"Channel Mapper", ONLY to do audio mapping one to one you can just skip it all and go stright to the encoder. It's more effective.
So, is your aim to get two discrete mono channels or one stereo channels in your output file?
-steinar
Re: how to extract two of three audiochannels from .mov?
Posted: Thu May 18, 2017 8:47 am
by ThomasM
Hey Steinar,
thank you for the reply. I have three audio-Channels. 1 and 2 is audio and 3 is LTC. For one encoding-situation I do not need the LTC-track, so I only want to encode the audio-tracks 1 and 2. But I cannot get it to work, neither with A/V-Media plus ChannelMapper nor without and going straight. Maybe I find some time to try a console-FFMPEG-command and put it into CustomFFMPEG-Node...
All the best,
tom
Re: how to extract two of three audiochannels from .mov?
Posted: Mon May 22, 2017 3:27 pm
by admin
Yes I understand that but what kind of channel layout are you trying to achieve? You're not stating that. As I have written before; if you select channel layout 2x1 (two mono streams) or 1x2 (one stereo stream) you should get your two audio channels.
Maybe you could post the output of "ffmpeg.exe -i "yourfile"" to this forum. It might show if there is something off with your media.
-steinar