[FFmpeg-user] mute audio without restart of encoding process

[Виктор Митрофанов]

Thank you for quick response!

2016-09-29 15:55 GMT+03:00 Moritz Barsnick <barsnick at gmx.net>:

> On Thu, Sep 29, 2016 at 13:38:06 +0300, Виктор Митрофанов wrote:
>
> > I need some way to mute audio in live rtmp stream while it is beign
> encoded
> > by ffmpeg.
> > Ideal scenario would be to have the ability to mute/unmute audio "on the
> > go" - without restarting ffmpeg and encoding process - is there any way
> to
> > make this possible?
>
> Sure, the zmq/azmq filter allows pushing commands to filters, to change
> their parameters at runtime. You would use "-af azmq,volume=1":
>
> $ ffmpeg -re -loglevel verbose -f lavfi -i anoisesrc -af azmq,volume=1
> -c:a libmp3lame test.mp3 -y
>
> Then using tools/zmqsend, you can send commands to the filter chain:
> $ echo 'Parsed_volume_1 volume 0' | tools/zmqsend
> (You can use any value which the volume filter can parse, such as
> "-20dB" or +"5dB", no spaces allowed though in this case apparently.)
>
> If you run ffmpeg with loglevel "verbose" (as in my example above), you
> can see the name of your filter within the chain, required for use with
> zmq, and the values it uses:
>
> [Parsed_volume_1 @ 0xbc44360] n:nan t:nan pts:nan precision:float
> volume:1.000000 volume_dB:0.000000
>
> As soon as I issue the above command with zmqsend, I get these
> messages:
>
> [Parsed_azmq_0 @ 0xbc42100] Processing command #0 target:Parsed_volume_1
> command:volume arg:0
> [Parsed_volume_1 @ 0xbc44360] n:289.000000 t:6.165333 pts:295936.000000
> precision:float volume:0.000000 volume_dB:-inf
>
> Note how the volume filter changes its amplification variable "volume"
> to 0, at time 6.165.
>
> Have fun with this,
> Moritz
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-- 
Best regards, Viktor Mitrofanov