[mythtv-users] Strange results with DVD rips

Fedor Pikus fpikus at gmail.com
Wed Jun 8 23:39:18 UTC 2005


I'm trying to rip a DVD and keep the AC3 stream, and I'm getting
really strange results: whatever I do, I can't get 6 channels.

I investigated and boiled down the problem to the simple test here:

# tcprobe -H 10 -i /dev/dvd -T 3
libdvdread: Using libdvdcss version 1.2.8 for DVD access
[tcprobe] DVD image/device
libdvdread: Using libdvdcss version 1.2.8 for DVD access
(dvd_reader.c) mpeg2 ntsc 16:9 only letterboxed U0 720x480 video
(dvd_reader.c) ac3 en drc 48kHz 6Ch 
(dvd_reader.c) DVD title 3/16: 2 chapter(s), 1 angle(s), title set 4
(dvd_reader.c) title playback time: 00:00:27.13  28 sec
(dvd_reader.c) [Chapter 01] 00:00:00.000 , block from 0 to 9740
(dvd_reader.c) [Chapter 02] 00:00:26.934 , block from 9741 to 9745
[tcprobe] summary for /dev/dvd, (*) = not default, 0 = not detected
import frame size: -g 720x480 [720x576] (*)
     aspect ratio: 16:9 (*)
       frame rate: -f 23.976 [25.000] frc=1 (*)
      audio track: -a 0 [0] -e 48000,16,2 [48000,16,2] -n 0x2000 [0x2000] 
[tcprobe] V: 672 frames, 28 sec @ 23.976 fps
[tcprobe] A: 0.44 MB @ 128 kbps
[tcprobe] CD:  650 MB | V:  649.6 MB @ 194604.5 kbps
[tcprobe] CD:  700 MB | V:  699.6 MB @ 209584.1 kbps
[tcprobe] CD: 1300 MB | V: 1299.6 MB @ 389340.0 kbps
[tcprobe] CD: 1400 MB | V: 1399.6 MB @ 419299.3 kbps

Note "ac3 en drc 48kHz 6Ch" - that's what I want. But next is  "audio
track: -a 0 [0] -e 48000,16,2 [48000,16,2]" - that's 2 channels, not
6. Mplayer agrees:

# mplayer dvd://3
hwac3: switched to AC3, 384000 bps, 48000 Hz
AUDIO: 48000 Hz, 2 ch, ac3, 384.0 kbit/25.00% (ratio: 48000->192000)
Selected audio codec: [hwac3] afm:hwac3 (AC3 through S/PDIF)
Checking audio filter chain for 48000Hz/2ch/ac3 -> 48000Hz/2ch/ac3...
AF_pre: 48000Hz/2ch/ac3
alsa-init: 1 soundcard found, using: iec958:{CARD 0 AES0 0x02 AES1
0x82 AES2 0x00 AES3 0x02}
alsa: 48000 Hz/2 channels/4 bpf/65536 bytes buffer/Signed 16 bit Little Endian
AO: [alsa] 48000Hz 2ch ac3 (1 bps)
Building audio filter chain for 48000Hz/2ch/ac3 -> 48000Hz/2ch/ac3...

Whatever I rip from this DVD ends up with 2 channels. So where are my
6 channels?!

-- 
Fedor G Pikus (fpikus at gmail.com)
http://www.pikus.net
http://wild-light.com


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