48 khz on SVCD?

[SHaque]

When I downsample audio from 48 khz to 44.1 khz (using TMPEG or toolame), it really sounds a lot worse. My Pioneer 434 plays 48 khz audio just fine. I was wondering if leaving the audio 48 khz would cause serious problems on other players? I wouldn't want to leave it like that if it renders it playable only on my own player.

Thanks!

[chainsaw135]

Well if your player is capable of playing 48khz you should try one that way. Because it will save you loads of time and sound better if you dont have 2 down sample. Most players now do support the 48khz.

[Antonio S.]

48 khz is out of (S)VCD standards... You may have problems in some players (Like is the case of Phillips DVD players)...

Antonio S.

[TactX]

Sound quality is not necessarily better if you keep 48 khz.

Assuming you use the same bitrate for both (48 and 44.1 khz) the 48 khz will have more information that has to be stored on the same amount of bits -> artefacts will be more audible in this case.

If we compare the uncompressed wave, the 48 khz file will always be better. But if you're using a good sample rate converter the difference will be very very small.

If you're using 224 kbit/s for audio, you can stick to 48 khz. But for lower bitrates (I use 192) you should convert to 441 khz (my opinion).

[chainsaw135]

I don't know if its my ears or what but i noticed a difference, between 48khz and 44.1khz. The difference wasent so bad i freaked out and was like "oh this is so much worse or better", but point being if the quality is better in some ways if not all ways then 48khz and works with your system and most new systems of today why down sample which takes like 30 minutes or more longer? Save your time and get better quality in my opinion.

[Yakumo]

Have got the same problem if I use tmpeg to convert 48khz to 44,1khz
So a friend told me to use virtual dub first and convert it there to 41,1khz. Use under audio full processing, then choose conversion, and there select 44100hz and high quality. Now save the wav again. Now use tmpeg to convert it to mp2 44.1khz file. Now the audio should be the same as the 48khz.
It workes for me :) Hoop this will help

[Doom9]

use ssrc as audio downsampler.. it gives the best quality. or.. even better... use besweet for direct ac3 to mp2 conversion with sampling rate conversion.. that's as good as it gets.

but.. if your player supports 48khz audio then there's no need for downsampling.. I effectively gave up downsampling for vcd/svcd as soon as I realized that my player actually supported 48khz audio

[bumblebe]

I've got a Raite 715 and the sound is just as bad whether it's 48khz or 44.1khz unlike on my PC where 48khz doesn't sound as metallic.

I'll try these downsamplers. Does BeSweet take .wav as an input ?

[DSPguru]

Originally posted by bumblebe
I'll try these downsamplers. Does BeSweet take .wav as an input ? BeSweet supports ac3/wav/mpa/lst for inputs.

[poopity poop]

for a good downsizer use sound forge, a REAL sound editing tool. IT has anti-alias fitlering which is good for non-multiple downsizing(interval meaning 44.1->22.05 is a multiple, so it 48->24, you get the idea).

SVCD's will not play in ANY DVD player if its not 44.1Khz

[TactX]

Listen to poopity poop.

Sound Forge is great.

[smiller667]

Originally posted by poopity poop
SVCD's will not play in ANY DVD player if its not 44.1Khz This should read "will not play in ALL DVD players if it's not 44.1kHz".

[Pko]

Originally posted by poopity poop
SVCD's will not play in ANY DVD player if its not 44.1Khz

All DVD player with SVCD capability I know of (Cyberhome, Shinco, Thomson, Daewoo, Sampo), play audio at 48KHz flawlessly if the SVCD is correctly done.

That is logic, since they are DVD players, and DVD audio is at 48KHz, so the chipset MUST be capable of playing audio at 48KHz. The SVCD standard imposes 44.1, and so 48 is out of spec, but most players play it. I am not sure if Philips really have trouble with 48KHz... I have heard many times that some player does not play VBR SVCDs, or that cannot play SVCDs with 2 audio streams, or streams generated with TMPGEnc or with BBMPEG or with this or that tool... Many times, the problem is that the SVCD was not correctly done in the first place; bad multiplexing, bad burning, bad bitrates... there are many posibilities to do something wrong when authoring a SVCD.

To really know if your player can play 48KHz, you need a SVCD that you know for sure is correct and change ONLY the samplerate of the audio; for example, you can do this:
- Download one of the SVCD samples from vcdhelp.com or vcdimager.org and make sure your player plays it OK
- Obtain the original structure and files of the SVCD with vcdxrip tool from vcdimager (with vcdeasy you can do that without ever going to the command line)
- Take the main sequence MPEG and demultiplex it with TMPGEnc
- Convert the MP2 demultiplexed (and expanded to WAV with Winamp) from 44.1 to 48 with TMPGEnc, at the same bitrate of the original
- Remultiplex the main sequence MPEG with the original .m2v and the new .mp2 using bbmpeg with the SVCD options, and name it like the original main sequence
- Make the bin+cue structure with vcdimager using the XML and files of the original, but with the new main sequence (again you can use vcdeasy)
- Burn the bin+cue to the apropriate medium (CD-R or CD-RW)

If you do that correctly, you have a SVCD that is 100% correct in everything but the audio sample rate. *IF* that SVCD (that is NON STANDARD) does not play well in your player, you are sure that the 48KHz thing is the cause. I have not found any player like that yet, but there are lots of different brands out there and perhaps is true that some players cannot play 48KHz.

[bumblebe]

well it plays even if it's 48khz but it seems to me some kind of downsampling must be going on because it sounds just as bad as a Tmpeg generated 44.1khz mp2 on my PC !

[Pko]

Originally posted by bumblebe
well it plays even if it's 48khz but it seems to me some kind of downsampling must be going on because it sounds just as bad as a Tmpeg generated 44.1khz mp2 on my PC !

Well, quality is just another matter... if your player can reproduce it, IMHO keeping the samplerate of the original data will be better than changing it, so if the original wav or ac3 was 48KHz, keeping the mp2 at 48KHz should give same or better quality than downsampling to 44.1.

Perhaps you are compressing too much... what bitrates are you using? you can do a test run compressing the original 48KHz wav to 48KHz MP2 at 224kbps, that should give you very good quality, if the original has good quality too, of course.

If you compress to 64, it will sound bad regardless it is 48KHz, 44.1KHz, 32KHz or whatever

[bumblebe]

I've been using 128kbps to save space and while the sound is really good on my PC, it's pretty poor on the Raite 715, that's why I thought it was maybe downsampling to get it to SVCD specs somehow.

[zambelli]

I hope you do realize that MP2 is inferior to MP3 and that 128kbps MP2 audio doesn't sound as good as 128kbps MP3 (and don't get me wrong, 128kbps MP3 is far from perfect, but well suitable for most DivX rips)?

Anyway, if you want really good downsampling and time is not an issue for you, use Cool Edit to downsample your WAV to 44kHz. It will take a while, but you shouldn't be able to tell the difference in the end.

[poopity poop]

sound forge is the best for downsampleing next to a professional sound editing studio...

mp2 is as inferior to mp3 as mpeg-2 is to mpeg-1, which is really not that noticable. So when you say you can notice a difference you must be a professional sound engineer, because there is not that much difference. But for DivX of course use mp3, and for vcd's and SVCD's use mp2 which you can stick a higher bitrate in anyway