problem encoding 448k audio - Is that cruddy noise I'm getti

[yukoncornel]

I am trying to create a SVCD of Things to Come. Everything went off without a hitch but the resulting audio on my SVCD sounds "tinny". Granted, the audio quality on that DVD was bad to begin with but there is a further degredation on the SVCD I encoded. Something I noticed was that the ripped DVD files showed the audio as being 48khz @448Kbps, and I only seem to be able to encode at a max of 224kbps with Tmpgenc. I used smartripper for the rip and dvd2avi to set up the encoding for Tmpgenc. So what I am guessing is that the audio was downconverted from 448kbps to 224kbps and the resulting tinny sound is hysteresis? I am guessing at this just because the sound I am getting is similar to what I got a few times when playing around with CoolAudio trying to get some sound files smaller so I could stream them from my web site. When making them smaller, that warbly, swishy, tinny sound apeared from changing the bit rate. Anyone got any comments??? Has anyone experienced something similar? Anyone ever seen a DVD with 448kbps audio? Thank You!!!
-Jon

<font size=-1>[ This Message was edited by: yukoncornel on 2001-09-14 11:53:46 ]</font>

[adam]

The tinny sound is caused by TMPGenc downgrading the kHz, not the bitrate. 224kbps is definitely sufficient for svcd audio in my opinion.

As good a video encoder as TMPGenc is, its audio encoder is known to have many quality issues. To prevent the tinny sound you can tell dvd2avi to downgrade the audio to 44100kHz. While this does provide sufficient quality, it is damn slow. A better option is to use an external frequency converter from withing TMPGenc. I use ssrc.exe. Go to option\environmental settings\external tool (only in more recent versions.)This will provide good quality at a decent speed.

It would also be a good idea to use toolame.exe as the external audio encoder, it is far superior to TMPGenc and I believe it is faster also. Again the option is in the external tool section. Click on layer-2 and point it toward the toolame.exe.

You can find toolame in the tools section and ssrc.exe is easily found through a web search or through links at http://www.doom9.net.

[yukoncornel]

Thanks Adam. I think what happened was that the SVCD I made that came out with the "tinny" audio was actually the first one I ever made. I used the default SVCD template that came with Tmpgenc, and it set the audio to 44khz. I have since made other SVCD's where I loaded the unlock template so I could access the khz setting for audio and keep it at 48khz so as to NOT have it converted, and the result played nicely on my Pioneer 525 DVD player with no "tinny" noise.

So, my next question is... Does it matter if do the 48khz->44khz conversion? Will keeping it at the originally ripped rate of 48khz cause any problems I am currently unaware of? I would think not since I did it with others and have yet to discover any problems. From other posts have read, the changes in audio settings don't seem to even have a huge bearing on file size. Your comments would be appreciated. thank You again.
-Jon

[adam]

48kHz is non compliant for both vcds and svcds. It might work on your dvd player but I can guarantee you that it wont on many players. For the sake of compatibility it would be best to always stick to the standard and downgrade to 44100, you never know when you might need to buy a new dvd player. Its also possible that if your svcd had higher bitrate for either the video or audio than it wouldnt be able to handle the 48kHz and the audio would start skipping.

As far as quality or size differences, no the two frequencies are basically so similar that you wouldnt notice a difference. The conversion does take some extra time but thats nothing compared to the encoding time for the video so my suggestion is that its better to be safe than sorry.