Audio filters FFMPEG in consumers

General
, ,
1

Hi,

I’ve tried several methods since I saw that Caspar could use FFMPEG filters. My idea is to use a compressor-limiter for the entire audio mix, hence the suggestions for Consumers, Decklink, and NDI, but I can’t get any of them to work, although I don’t see any errors in the log either.

I’m using version 2.5.0.

<custom-filters>compand=attacks=0.1:decays=1.0:points=-90/-90|-35/-25|-15/-9|0/-5:soft-link=6:gain=2:delay=0.1,alimiter=limit=0.95:level=1</custom-filters>

I’ve also tried using the tags “audio-filter”, “custom-audio-filters”, but I can’t get it to work, even though I don’t see any filter loading errors in the log.

  <audio-filter>volume=0.9</audio-filter>

I’m trying to implement these filters in consumer settings, using DeckLink and NDI.

<decklink> <device>1</device> <embedded-audio>true</embedded-audio> <latency>low</latency> <custom-filters>compand=attacks=0.1:decays=1.0:points=-90/-90|-35/-25|-15/-9|0/-5:soft-link=6:gain=2:delay=0.1,alimiter=limit=0.95:level=1</custom-filters> </decklink>

`<ndi>
 <name>playout</name>`

<latency>low</latency> <audio-filter>volume=0.9</audio-filter>
</ndi>
</consumers>

Thanks.

2

CasparCG does use FFmpeg for both decoding source content and making recordings or streaming a channel output.

The only XML tags processed on startup are those listed in the “commented out” section of casparcg.config so your tag is ignored. Similarly the and you tried to attach to the ndi consumer are ignored.

You can apply an FFmpeg audio or video filter to a source file. For example to filp the video and apply a 500 Hz audio low-pass filter (i.e use default values in the filter) you send a play command such as:

PLAY 1-10 "myfilename" vf hflip,vflip af lowpass

If you are using the SVT client to control CasparCG you can put the above command line into the F2 box of the custom command. Similarly you can add a stop command issued by the F1 key using the string:

STOP 1-10

Filter properties are set when the file is either loaded into the background or played. As best I can recall the filter properties can not be changed by a call command on the channel/layer.

The volume of a layer and the overall volume of a channel can be adjusted using the AMCP mixer commands, but there is no provision for manipulating the audio dynamics.