[FFmpeg-devel] ffmpeg g723

[Zalewa PL]

Robert Watson wrote:

> I need to stream from the card to a red5 server so I don't think this would
> work.
> Robert
>
> On Sat, Mar 10, 2012 at 1:30 PM, Zalewa PL<zalewapl at gmail.com>  wrote:
>
>> Robert Watson wrote:
>>
>>> I was wondering if you could help with using ffmpeg to process the audio
>>> input from a capture card.  The card has v4l2 and alsa drivers. The card
>>> outputs G.723-24 (3-bit samples at 8khz).  Was the g723 code you wrote
>>> committed into the ffmpeg core?  What command line should I use to capture
>>> the audio from the card?
>>> Thanks, Robert
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>>>
>> Hi,
>>
>> You can use 'decode-g72x' tool to convert data in G.723-24 format to raw
>> PCM that can be forwarded to ffmpeg. The source code of the tool is
>> available here:
>> //http://www.ps-auxw.de/g72x++**.tar.bz2<http://www.ps-auxw.de/g72x++.tar.bz2>
>> The compilation is straight forward. Once you get the executable file you
>> can run it like this:
>> `arecord -Dhw:1,0 -traw | decode-g72x -l -3 | ffmpeg -acodec pcm_s16le -f
>> s16le -ar<rate>  -ac<channels>  -i - /tmp/output.wav`
>> I'm not sure if all parameters that I have specified here are correct but
>> I'm sure you can figure it out. Write if you have any further problems.
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>>
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I don't know how the red5 server works exactly.
Does it start ffmpeg child processes basing on what is written in its 
configuration file? If so then it's similar to ffserver. Perhaps there 
is a way to launch the child processes manually? ffserver allows that.

If that is not an option you could also forward decode-g72x output to a 
named pipe and then use ffmpeg to read the data from that named pipe.