FFAStrans forum

Hi there,

just stumbled ´bout this problem:

I want to insert a conditional node which locates the number of audio channels in the original file. Example: DV-Files with two or for audio-Files. I want to convert these to different formats, some with 4 audio-tracks, some only with the first two audio-tracks depending on target-format.

ALL input is DV-material in .mov container

node-list test1:

1. Folder-Node
2. conditional-Node with %i_a_streams% IS = 2 THEN -> Encoder-Node A -> Output-Folder-Node
3. conditional-Node with %i_a_streams% IS > 2 THEN -> A/V-Media-Node All set to intelligent -> ChannelMapper-Node -> Encoder-Node B -> Output-Folder-Node


node-list test2:

1. Folder-Node
2. A/V-Media-Node All set to intelligent
3. conditional-Node with %i_a_streams% IS = 2 THEN -> Encoder-Node A -> Output-Folder-Node
4. conditional-Node with %i_a_streams% IS > 2 THEN -> ChannelMapper-Node -> Encoder-Node B -> Output-Folder-Node

ALL DV-Material is 2-Channel (stereo...) but I get only 4-channel exports - what do I do wrong?

regards,

tom

Hi Tom,

The current version (0.7.7) cannot obtain the audio layout in a good fashion. The "%i_a_streams"-variable will tell you how many audio streams there are, not the channel count. Streams and channels are not the same. The new version (0.8.0) will have a variable for the total number of channels in the media but it wont tell you the audio layout.

In your node-list test2 you're using the "A/V Media"-decoder. It will ALWAYS give you ONE stream with 32 channels, so the conditional test must be done prior to the decoder.

What kind of encoder are you using?

-steinar

Steinar,

thank you for this answer. It´s great news that 0.8 will have a audio channel-variable.

If I would have read carefully I should be aware of "streams" and "channels"... Sorry for that. It´s clear.

I wanted to encode to DV (DVCpro) (2 or 4 channels) and mpeg4 (2 channels only, kick channel 3 and 4 if present).

Regards,

tom

Hey Steinar,

I discoverd this variable: %i_a_channels% but it´s the same result...

cheers,

tom

once again, the output in the FFAStrans Monitor is:

Conditional@machine : 1st evaluation of "%i_a_channels%>2" is "2>2" - does this make sense?

regards, tom

Yes it makes sense. The evaluation failed because the condition was not met. 2 is not larger than 2.

And I'm sorry to have misled you. I simply forgot the %i_a_channels% variable. My bad. But it does what you expect; counts the total number of channels regardless of the layout.

The current DV-encoder supports 2 or 4 channels. You just use the conditional to decide if your source has 2 or 4 channels and send them to each corresponding encoder with two different settings (2 and 4 channels).

Additionally, it may be easier if you send me or post the workflow and I'll have a look at it and see if it's valid.

-steinar