-map_audio_channel and -map conflict about ffmbc HOT 8 CLOSED

-vn and -an disable video and audio respectively, the first command line is 
bogus.

-map_audio_channel overrides -map obviously

Apologies, -vn and -an are strictly unnecessary to replicate the problem but 
they make explicit what the output to the respective pipes is. The first is 
purely video, hence the -an, the second is purely audio, hence the -vn and the 
-newaudio post the filename to reinsert an audio stream.

And unfortunately -map_audio_channel does not override -map, hence the audio 
file in the second example being full of 0s without correctly mapped essence as 
specified by the map_audio_channel directives.

Though the -an and -vn are unnecessary to replicate the problem, removing them 
will leave identical and still broken behaviour. I would ask you to please 
re-examine the command lines and try again to replicate the erroneous 
behaviour, it definitely exists and definitely breaks valid use cases

To perhaps further clarify;
* The key problem is that you cannot have one map directive without having a 
map directive for every output stream, and map_audio_channel does not count 
towards this
* This is compounded by the fact that if you do specify a 'placebo' map 
statement for an output stream you wish to supply more detailed 
map_audio_channel directives for, the map overrides the map_audio_channel 
directives, rendering them useless

Err yes, -map overrides -map_audio_channel

It's one -map for each output stream like the error message say.

What you describe is expected behaviour. I'm not sure what you are asking here.
Do you want the behaviour changed ? If so, that's not planned currently.

First, thanks for checking on the issue and reading my comments.

If this is expected behaviour then perhaps I'm trying to do something 
impossible. I can understand why there has to be a map per output but my 
limited understanding of ffmbc is such that I was viewing map_audio_channel as 
a refinement of map's behaviour, with additional granularity.

Hence, in the case stated above, where I take N input streams and map them to 2 
output streams, but where the 2nd has M audio channels, I was hoping to use 1 
map statement and M map_audio_channel statements and to have the fact that 
there was at least one map_audio_channel to the 2nd stream count as a map 
statement for validation purposes:

input              output

a1       ->          b (video stream, has -map)
a2
         ->          a2 (audio stream, 4 channels, has 4x -map_audio_channel and no -map)
b                    c2
                     d1
c1                   d2
c2

d1
d2

Is this breaking the model? If so, how might I go about achieving this sort of 
mapping?

Thanks again for spending the time replying

Hi Baptiste,

Lets say I want to output an pal-imx30, and my input file is a .ts with two 
video streams and two audio streams each with two audio channels.

Perhaps I want the pal-imx30 file to contain the second video stream and all 
four audio channels from the input.

I will need to -map the video and -map_audio_channel the audio. But the moment 
I -map the video I have to -map the audio to comply with the one-map-per-output 
requirement. Having a -map for the audio means I cannot make a four channel 
audio stream, and even if I was happy with a two channel output stream -map 
overrides -map_audio_channels.

I think what Paul was requesting is for -map_audio_channel into a -newaudio 
needs to count as though it were a -map.

Does that make any sense?

Hey Mark,

Yes I understand the case. It should work if the first video stream is the 
wanted one though, since in this case -map is not needed.

It should now work in 0.7-rc1