[MPlayer-users] Re: rm -> pcm (then to mp3) and timing a stream

[adland]

> is there a way to do
> the encoding to mp3 at the same time?


could try

#!/bin/bash

if [ $# -ne 2 ]; then
   echo "Usage: "$0" <input> <output>"
else
   mkfifo MYFIFO
   ./mplayer -really-quiet -ao pcm -aofile MYFIFO -vo null -vc dummy "$1" &
   lame -b 128 MYFIFO "$2"
   rm MYFIFO
fi


> Next, I want to capture an hour out of an archive rm file.
> 
> Now, luckily, it turns out the rstp address  will take a ?start=h:m:s
> parameter to seek to a position, so I'm able too start where I like.

two ideas
1. try adding a stop parameter to rtsp stream argument as well.
ex
rtsp://stream?start=h:m:s&stop=h':m':s' to adjust length of file streamed.

2. modify above to count blocks being written to audio pipe 
   based on bitrate and blocksize used you could calculate a value
   we set blocksize to 1 and count to 
   (bitrate*channels*bytes per sample*seconds) + 48 bytes for wave header
    44100*2*2*3600)+48=  635040048 bytes into lame encoder for an hour

this is just a quick example be sure to edit the X value for some
 integer calculated for length desired

CD audio is 44.1 Khz bitrate, 2 channels, 2 bytes per sample

also of course you may want/need different lame options
see unix manpages of commands for more help

#!/bin/bash
# encode some seconds of audio from infile into outfile as mp3.
# count should be set to (bitrate of input * channels * bytes per sample 
# * # of seconds) + 48 header bytes
# when blocksize (bs) is set to one byte
# for dd you can also add skip=Y to skip first section of audio if desired

if [ $# -ne 2 ]; then
   echo "Usage: "$0" <input> <output>"
else
   mkfifo AOFIFO
   ./mplayer -really-quiet -ao pcm -aofile AOFIFO -vo null -vc dummy "$1" &
   dd bs=1 if=AOFIFO count=X |  lame --quiet -b 128 - "$2"
   # stop mplayer in background and cleanup
   killall -9 mplayer
   rm AOFIFO
fi

good luck