#1258: Codec support request : MPEG Multichannel Audio
-------------------------------------+-------------------------------------
Reporter: aquarat | Owner:
Type: enhancement | Status: new
Priority: normal | Component: FFmpeg
Version: unspecified | Resolution:
Keywords: mpeg | Blocked By:
mctoolame multichannel | Reproduced by developer: 0
Blocking: |
Analyzed by developer: 0 |
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Comment (by aquarat):
I've included mctoolamed-01a.tgz, which is also available on Sourceforge.
I've also included my modified version of the code "lamedecoder"... my C++
skills are really bad, so I've highlighted the changes I've made below. I
also tried modifying the code to change the output file names depending on
the input file name... but yeah, C skills are lacking.
To compile mctoolamed on Debian you need to change the architecture in the
Makefile. I changed it to "core2" to get it to run on my Core-based
machine (Intel Xeon).
I had to modify part of the code to get it to handle 4 channel files :
in audio_write.c : I modified the soundfile array
Original :
{{{
char soundfile[MTYPES][MAXCHANNELS][256] = {
{"left.wav", "right.wav", "centre.wav", "left_surround.wav",
"right_surround.wav"},
{"left.wav", "right.wav", "centre.wav", "lfe_this_may_not_play.wav",
"left_surround.wav", "right_surround.wav"}
};
}}}
Revised :
{{{
char soundfile[MTYPES][MAXCHANNELS][256] = {
{"left.wav", "right.wav", "centre.wav", "left_surround.wav",
"right_surround.wav"},
{"left.wav", "right.wav", "centre.wav", "lfe_this_may_not_play.wav",
"left_surround.wav", "right_surround.wav"},
{"left.wav", "right.wav", "rearleft.wav", "rearright.wav"}
};
}}}
The "waveheader" array has the sample rate flag set for 44.1kHz. If left
unchanged the resulting files will play back slower than they should.
Modification to handle 4 channels :
Original :
{{{
void init_audio_outputs(int numchan) {
int i,j;
int type=-1;
numchannels = numchan; // Set the global var for later on.
if (numchan == 5)
type = 0;
if (numchan == 6)
type = 1;
if (soundfile>=0) {
fprintf(stderr,"initialising %i output files\n",numchannels);
for (i=0;i<numchannels;i++) {
if ( (audioout[i] = fopen(soundfile[type][i], "w")) == NULL ) {
fprintf(stderr,"Error opening %s for
output\n",soundfile[type][i]);
exit(99);
}
/* Write a really dodgy wave header */
/* Fix this to write the proper sampling frequency */
for (j=0;j<WAVEHEADERSIZE;j++)
fputc(wave_header[j], audioout[i]);
}
}
}
}}}
Revised :
{{{
void init_audio_outputs(int numchan) {
int i,j;
int type=-1;
numchannels = numchan; // Set the global var for later on.
if (numchan == 5)
type = 0;
if (numchan == 6)
type = 1;
if (numchan == 4)
type = 2;
if (soundfile>=0) {
fprintf(stderr,"initialising %i output files\n",numchannels);
for (i=0;i<numchannels;i++) {
if ( (audioout[i] = fopen(soundfile[type][i], "w")) == NULL ) {
fprintf(stderr,"Error opening %s for
output\n",soundfile[type][i]);
exit(99);
}
/* Write a really dodgy wave header */
/* Fix this to write the proper sampling frequency */
for (j=0;j<WAVEHEADERSIZE;j++)
fputc(wave_header[j], audioout[i]);
}
}
}
}}}
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1258#comment:1>
FFmpeg <http://ffmpeg.org>
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