[MPlayer-users] Re: Again on 5.1 vorbis encoding
marcogi at libero.it
marcogi at libero.it
Mon Jan 6 21:28:38 CET 2003
On Mon, 6 Jan 2003 marcogi at libero.it wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> On Sun, 5 Jan 2003, Alessio Sangalli wrote:
>
> > I've got the idea. I'll try to encode in separate steps so I can
> > compare
> > the file sizes of the ac3, pcm, vorbis data in 5.1 and stereo modes.
>
> I did this just yesterday. Here what I got:
>
> $ du -m
> 205 stream.ac3
> 218 3.ogg
> 221 4.ogg
> 258 5.ogg
I remade encoding test from ac3 5.1 to 6 channel vorbis, since previus
ones were wrong encoded.
I forgot to specify sempling rate to oggenc so it defaults to 44100
while .wav file was 48000 Hz.
I'm very sorry.
Now test results.
Original AC-3 file:
205 MB - File length: 74m 31,0s
ATSC A/52 aka AC-3 aka Dolby Digital stream, 48 kHz,,
complete main (CM) 3 front/2 rear, LFE on,,
384 kbit/s reserved Dolby Surround mode
Wave file created using:
mplayer -channels 6 -ao pcm ...
Vorbis files encoded using:
oggenc -q <quality> -C 6 -R 48000 -o file.ogg file.wav
Here what I got:
Quality | Avg bitrate (kbps) | File size (MB)
----------------------------------------------
0 | 181,9 | 98
1 | 244,2 | 131
2 | 327,3 | 175
3 | 378,5 | 202
4 | 386,9 | 207
5 | 458,4 | 245
The problem with these 6 channels vorbis files is that mplayer plays they
incorrectly. About firsts 95 secs are played correctly, but after that
only 2 rear channels are earable.
Someone can reproduce this? Am I doing something wrong?
--
Regards, Marco Gigante
Student at Pisa University - Computer Engineering
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