VOGONS


First post, by Demetrio

User metadata
Rank Newbie
Rank
Newbie

Hi, I have an old pc from the mid '90s, borrowed from a friend of my father, in which I've installed Damn Small Linux and MS-DOS 6.22 in dual boot.
It works well; I can play games, go on the Internet, code...
I can also play mp3s, both in DOS and in DSL, but I noticed that they are played slightly slower.
I don't know why, maybe the CPU cannot play these files perfectly, I really don't know.
All the mp3s have 320 kb/s bitrate and 44100 Hz sample rate.
PC has:

  • CPU: AMD K5 90 MHz
  • RAM: 32 MB
  • Audio card: CMI8330

Thanks in advance.

Reply 1 of 25, by darry

User metadata
Rank l33t
Rank
l33t

Some ultra cheap CMI8330 based cards do not have an onboard oscillator and use a clock signal provided by the motherboard, which may not be the right value for proper playback speed .

EDIT : See Re: Sound Blaster 16 Clones
Maybe adjusting your ISA BUS clock speed in BIOS will help .

Reply 3 of 25, by rmay635703

User metadata
Rank Member
Rank
Member
Demetrio wrote on 2020-06-02, 22:43:

If I reduce mp3 bitrate, there's a chance that the playback speed will improve?

Improve how?

Audio accuracy, probably not
Audio loading time, skipping and buffering = better

Reply 5 of 25, by darry

User metadata
Rank l33t
Rank
l33t
Demetrio wrote on 2020-06-02, 22:43:

If I reduce mp3 bitrate, there's a chance that the playback speed will improve?

If CPU speed is insufficient, audio playback will skip, not slow down .

The slow playback speed is likely due to the card receiving an inappropriate clock signal, so lowering bitrate will not help at all .

Test it with an uncompressed wav file, you should have the same issue .

To fix this, you would probably need to modify the card by adding a proper clock oscillator (there used to be instructions on the Internet about how to do this, but I cannot locate them) . As mentioned before, if you are lucky, maybe changing the ISA bus clock speed in your BIOS will help (if you have such an option) .

Reply 6 of 25, by derSammler

User metadata
Rank l33t
Rank
l33t
darry wrote on 2020-06-02, 22:50:

If CPU speed is insufficient, audio playback will skip, not slow down .

Wrong. It will slow down with most MP3 decoders. Only a few skip actually, as they clear the buffer during playback (like Winamp e.g. does).

There's no way for a K5 with 90 MHz to play 320kbps MP3s. You need Pentium 75 speed for 128kbps joint stereo already.

Reply 7 of 25, by matze79

User metadata
Rank l33t
Rank
l33t

K5 90Mhz is faster then P75..

https://dosreloaded.de - The German Retro DOS PC Community
https://www.retroianer.de - under constructing since ever

Co2 - for a endless Summer

Reply 8 of 25, by derSammler

User metadata
Rank l33t
Rank
l33t

No, it's not. MP3 uses floating point for decoding at which the K5 sucks. Also, you'd need that speed for a 128kbps joint stereo file, but he is trying to play 320kbps simple stereo files that need about 3 times as much horse power.

Reply 9 of 25, by darry

User metadata
Rank l33t
Rank
l33t
derSammler wrote on 2020-06-03, 11:10:
darry wrote on 2020-06-02, 22:50:

If CPU speed is insufficient, audio playback will skip, not slow down .

Wrong. It will slow down with most MP3 decoders. Only a few skip actually, as they clear the buffer during playback (like Winamp e.g. does).

That has not been my experience when attempting playback back in the day on a 486 with the multiple Windows players I tried at the time (among which Winplay3 and Winamp) . All of them skipped (presumably when the buffer underflowed) . I would imagine that slow playback could happen if the player has trouble even feeding rhe sound card fast enough from its buffer (if it has one), because the PC is really much too slow, but that would still give at least glitchy audio as samples would certainly be dropped unevenly, which is not what the OP described . Please provide examples of MP3 players that provide slower glitch-free playback on underpowered machines (I am of course not referring to the ones that let you adjust the playback speed intentionally, that is different).

Anyway, I suggested playing back a wave file to be sure it was a sound card clock issue and not related to MP3 decoding capability.

Reply 14 of 25, by zyga64

User metadata
Rank Member
Rank
Member

You can try older Winamp (2.x line) it has mp3 decoder which can be configured for older processors
zkqNisq.jpg

Image is taken from this thread Lowest CPU to play MP3s?

1) VLSI SCAMP /286@20 /4MB /TVGA9000C /CMI8330
2) i420EX /486DX33 /16MB /Trio64V+ /AZT2316
3) i430HX /P233MMX /64MB /VirgeDX+3DFX /YMF701
4) i440BX /P II 400 /256MB /FX5500/AWE64
5) i865G /E5800 /2GB /Ti4200 /YMF724

Reply 15 of 25, by darry

User metadata
Rank l33t
Rank
l33t
zyga64 wrote on 2020-06-04, 06:27:
You can try older Winamp (2.x line) it has mp3 decoder which can be configured for older processors https://i.imgur.com/zkqNisq. […]
Show full quote

You can try older Winamp (2.x line) it has mp3 decoder which can be configured for older processors
zkqNisq.jpg

Image is taken from this thread Lowest CPU to play MP3s?

Winplay3 is also worth a shot. It is very old and optimised for the machines of its era .

But if that wav file played slower than normal, it is still strange . Was the wav file the same as song as one of the MP3s you tried? It would make the comparison easier .

Reply 16 of 25, by Demetrio

User metadata
Rank Newbie
Rank
Newbie
darry wrote on 2020-06-04, 06:33:

But if that wav file played slower than normal, it is still strange . Was the wav file the same as song as one of the MP3s you tried? It would make the comparison easier .

Yes, it was.
The wav has the same sample rate of the mp3 and a bitrate of 1411 kb/s.
Like the mp3s, I tested it by playing it with the same song on my phone at the same time: it seemed that it was tiny slower but maybe I perceived wrong.
I didn't tested a lot so I can be wrong.

Reply 19 of 25, by Demetrio

User metadata
Rank Newbie
Rank
Newbie
pii_legacy wrote on 2020-06-04, 18:24:

The first reply of this thread told you exactly the problem so why waste so much time testing it? If a 68000 can play an MP3 (as long as it's the only thing it's doing), your CPU is capable.

Other posts said that it could be the CPU so I wanted to be sure.
The CMI8330 is connected directly to the motherboard so I don't know how to fix this; maybe I will buy another audio card.