[MPlayer-users] Patch to make the "-ao pcm" wav output supporting pipes.

[Alain Daurat]

Dear users of MPlayer,

I join  a patch against Mencoder 0.90rc2 which permits
to make pipes for the wav pcm output of mplayer.

With the 0.90rc2 it is impossible to do this.
For example the following commands:
--
rm audiodump.wav
mkfifo audiodump.wav
mplayer -ao pcm -waveheader -vo null  test.avi < /dev/null &
lame audiodump.wav aa.mp3
--
always produces a  aa.mp3 of length 0.

It is because that when the file is not finished to be written,
it has a temporary length of 0. It is more logical to
write an infinite length. (sox does this)
So I change 2 lines in libao2/ao_pcm.c to write infinite
instead of zero.
(PB: the infinite is in fact 2G which is only 3 hours for a 
 48khz/16bits/stereo sound, but it is an intrinseque limitation
 of the WAV format ??)

I have also modified the script mencvcd, because thanks to
the previous modification, we don't need to use a file where there
is all the uncompressed audio data.

Alain

PATCH: (between the '##################')
#########################################
--- libao2/ao_pcm.c.ori	Sat Nov  2 22:54:08 2002
+++ libao2/ao_pcm.c	Sun Jan 19 15:51:48 2003
@@ -50,7 +50,8 @@
 /* init with default values */
 static struct WaveHeader wavhdr = {
 	le2me_32(WAV_ID_RIFF),
-	le2me_32(0x00000000),
+        /* same conventions than in sox/wav.c/wavwritehdr() */
+	le2me_32(0x7ffff024),
 	le2me_32(WAV_ID_WAVE),
 	le2me_32(WAV_ID_FMT),
 	le2me_32(16),
@@ -61,7 +62,7 @@
 	le2me_16(4),
 	le2me_16(16),
 	le2me_32(WAV_ID_DATA),
-	le2me_32(0x00000000)
+	le2me_32(0x7ffff000)
 };
 
 static FILE *fp = NULL;
--- TOOLS/mencvcd.ori	Sat Nov  2 18:27:23 2002
+++ TOOLS/mencvcd	Sun Jan 19 15:51:48 2003
@@ -166,6 +166,7 @@
 rm -f $AUDIO
 # create a named pipe for video stream
 mkfifo -m 660 $VIDEO
+mkfifo -m 660 $AUDIO
 
 # some inits
 sub=""
@@ -331,35 +332,29 @@
          mpeg2enc -v 0 -s $mpegnorm -S $CDMAXSIZE -g 6 -G 15 -r 16 \
 	          $framerate $yuvin -4 2 -2 1 -o $NAME.mpv) &
    
-      # wait for finishing the subprocesses
-      wait
-
       # do resampling with sox
       if [ $sox -ne 0 ]; then
-	echo "wait, do resampling with sox..."
-	sox $AUDIO -v $volume -r $asr $NAME.wav resample -qs
-	mv -f $NAME.wav $AUDIO
+        soundcmd="sox -t .wav - -v $volume -r $asr -t .wav - resample -qs"
+      else
+        soundcmd=cat
       fi
 
       if [ $toolame -ne 0 -a $mp3 -eq 0 ]; then
 	# do mp2 encoding with toolame
-	echo "wait, encoding to mp2 audio with toolame..."
-	toolame -b $abr $AUDIO
-	mv -f `basename $AUDIO .wav`.mp2 $NAME.mpa
+	$soundcmd < $AUDIO | toolame -b $abr - $NAME.mpa &
       elif [ $toolame -eq 0 -a $mp3 -eq 0 ]; then 
         # mp2enc/lame can't read audiodump.wav directly from named pipe,
         # we have to read the whole file.
-	echo "wait, encoding to mp2 audio with mp2enc..."
-        mp2enc -b $abr -r $asr -o $NAME.mpa < $AUDIO
+        $soundcmd < $AUDIO | mp2enc -b $abr -r $asr -o $NAME.mpa &
       elif [ $mp3 -ne 0 ]; then
-	echo "wait, encoding to mp3 audio with lame..."
-        lame -b $abr --resample $kasr - $NAME.mpa < $AUDIO
+        $soundcmd < $AUDIO | lame -b $abr --resample $kasr - $NAME.mpa &
       fi
+      
+      
+      # wait for finishing the subprocesses
+      wait
    fi
 
-   # remove wav file, won't need anymore!
-   rm -f $AUDIO
-
    # multiplex streams
    [ -f $NAME.mpv -a -f $NAME.mpa ] || exit 1
    rm -f ${NAME}*.mpg
@@ -367,6 +362,7 @@
 
    # remove pipe, won't need anymore!
    rm -f $VIDEO
+   rm -f $AUDIO
    
    # should i create only the mpeg file?
    [ $mpgonly -eq 1 ] && exit 0
#########################################################################