MP3@64 stuttering and skipping

[AmigaNut08]

Hi all. It seems that i am not having any luck at all with any new Amiga hardware i get these days. I just tried out my new MP3@64 Audio decoder in my A1200 only to have the audio skip and stutter so bad that it is torture to try and listen too it. I am using the mp3at64mpeg.device and Amplifier to play the mp3's. I tried different settings but to no avail. After thinking that Amplifier might be the problem i tried an mp3 with the shell based player that comes with the mp3at64mpeg.device, mp3at64play but i get the same results.

 In the readme is the following.

Known Problems
~~~~~~~~~~~~~~
- Sometimes the sound is interrupted for a short period. Seems to be a  bug
  in  the  timer.device  that  sometimes causes interrupts to be delayed. I
  tried very small intervals, but it still remained, so I guess it's either
  a bug in timer, or the system interrupt load causes high latencies.

Is anyone else getting stuttering and skipping audio or is it just my luck to be the only one affected??? If others are getting smooth playback i'll try this card in my A2000 equipped with a Buddha Phoenix card, which is the Amiga i intended to use this on originally.

[Colani1200]

What OS are you running on your A1200? Maybe something is interfering. You might try to boot without startup-sequence and check if you get better results with the command line player then (not sure if this will work though).

[AmigaNut08]

What OS are you running on your A1200? Maybe something is interfering. You might try to boot without startup-sequence and check if you get better results with the command line player then (not sure if this will work though).

I am running OS3.1. Although the MP3@64 is not meant to put a load on the Amiga's CPU the Apollo 1240 (040@40Mhz) felt some strain as the system was very laggy and the screen flashed black very quick(like a blink) on 2 occasions while playing mp3's.

 I was going to try the command line player with no startup- sequence but i then got side tracked and forgot. I cant be bothered opening the A1200 up now to try, plus i am more anxious to see how it performs in the A2000, which is the Amiga i really want to use it in.

Cheers

[MozzerFan]

I'm using it in my A4000/060 on the clockport of my Xsurf card, and when playing MP3s and shoutcast streams I have smooth playback with Amplifier, AmigaAmp, Streamer and AminetRadio.
Only occasionally sound is interrupted.

[x303]

Have you tried to make the (pre)buffer as big as possible ? If set to low, you'll get the effect as described.

x303

[pan1k]

How much RAM do you have installed?

[Daedalus]

Sorry, bit late onto this thread, but can any of you confirm that you're using the MP3@64 off the internal clockport on an A1200? And if so, how did you achieve this? Using a clockport riser I guess? Also, how is performance? Like, what's the highest bitrate you can play on your machine and with what software?

I'm currently using a MAS player for an ongoing MP3 jukebox project, and I might consider going the MP3@64 route if it's less CPU hungry than the current parallel port transfers...

[alexh]

I'm currently using a MAS player for an ongoing MP3 jukebox project, and I might consider going the MP3@64 route if it's less CPU hungry than the current parallel port transfers...

The only CPU power I can imagine is used in MAS is accessing an IDE hard drive. If you have a DMA capable hard drive then it should be very little.

The same overhead will be present if you switched to MP3@64

[AmigaNut08]

Have you tried to make the (pre)buffer as big as possible ? If set to low, you'll get the effect as described.

x303

I tried double the standard setting and then tripled the values. But still not acceptable. I'll try some over the top values and see if that helps next time.

[AmigaNut08]

How much RAM do you have installed?

I have 18 meg all up. the standard 2 meg chip on the A1200 and 16 meg on the Apollo 1240. After boot up and the player loaded, i have over 13meg free.

[Daedalus]

The only CPU power I can imagine is used in MAS is accessing an IDE hard drive. If you have a DMA capable hard drive then it should be very little.

The same overhead will be present if you switched to MP3@64

Well, I'm trying to keep to as little additional hardware as possible, so it's a bog standard A1200 with an 030/16 and a hard drive at the moment and little else. Surprisingly, the MAS does use a bit of CPU power, and I guess uses a lot of interrupts for its tight timing. It uses the parallel port, but not in parallel, if you get me - all the data has to be converted in software to serial for the I2C bus that the MAS chip requires. If the MP3@64 didn't need to do that conversion, it should be easier on a little machine like mine...

Especially since I'm writing the software and it's not exactly efficient

[AmigaNut08]

Sorry, bit late onto this thread, but can any of you confirm that you're using the MP3@64 off the internal clockport on an A1200? And if so, how did you achieve this? Using a clockport riser I guess? Also, how is performance? Like, what's the highest bitrate you can play on your machine and with what software?

I'm currently using a MAS player for an ongoing MP3 jukebox project, and I might consider going the MP3@64 route if it's less CPU hungry than the current parallel port transfers...

I did use the MP3@64 off the internal clockport on my A1200. I used a clockport extension cable (Male header to Female header) that i ordered from Amigakit. The MP3@64 can play any bit rate. The player i used was Amigaamp. The sound quality (when it did not stutter) is brilliant. I would recommend purchasing the MP3@64 as it decodes the MP3 audio without the use of the Amiga's CPU. Now if only it played without stuttering. I am going to have to try this in my A2000 this weekend and see if it performs better.

[Daedalus]

Thanks for that! Yeah, it's the stuttering I'm worried about - I was thinking it could be a factor of DMA timing or something which affects certain A1200 motherboards. The MAS Player uses the same decoding chip as the MP3@64, but like I said in my previous post, just takes a little bit of CPU power to do a serialisation of the data before sending it out the parallel port. It's a shame there's nobody living nearby I could borrow one from to test it

[keropi]

I have an mp3@64 connected to the clockport of a kickflash in my A4000/CSPPC ... quality is EXCELLENT, and it even plays 320kbps VBR mp3's without problems... only the little delay pops now and then, as Chris explains in the readme...

[AmigaNut08]

Thanks for that! Yeah, it's the stuttering I'm worried about - I was thinking it could be a factor of DMA timing or something which affects certain A1200 motherboards. The MAS Player uses the same decoding chip as the MP3@64, but like I said in my previous post, just takes a little bit of CPU power to do a serialisation of the data before sending it out the parallel port. It's a shame there's nobody living nearby I could borrow one from to test it

DMA timing is what i am thinking also. Remember the timing issues A1200's had when faster cpu cards came out for it. A mod had to be performed on the mobo because of timing issues. I was also unable to get my ethernet adapter to work through the credit card slot as i was told my mobo also needed a mod done because the port would not reset with the given software. I was unable to connect to my router so i ended up selling the ethernet card. Not all A1200's suffer from these above mentioned issues (thank god the Apollo1240 worked as i believe this mobo was modded before i bought it) but knowing my luck i am probably in the minority of people that have had issues like this.

PS: Anyone out there using the MP3@64 in an A1200??