how to extract two of three audiochannels from .mov?

[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

[admin]

Hi ThomasM,

What encoder are you using?

-steinar

[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

[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

[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

[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