Max bitrate SVCD on stand alone?

[Peter]

Most players play SVCD up to 2500 kbit/s.
Why is that?
DVD is also MPEG2 and goes much higher.

[adam]

The max bitrate of svcds is determined by the maximum speed at which the dvd player can read the cdr, which is only 2x. So the way the max bitrate is determined is:
Max bits per second = (2324 byte per sector) × (75 sectors per second) × (8 bits per byte) × (2 times CD read speed) = 2,788,800 or ~2790 kbits/sec. This inclues both audio and video bitrates.

Dvd media can be read much faster which is why it can have such a high bitrate.

[aldus4]

@adam

From what I understand does that mean that when the so-called 3rd generation DVD players (with speeds of 5x) eventually arrive, SVCD's could be read at a higher bitrate?

[Vejita-sama]

Yes, in fact there are stand alones that will do 5000kbit/s w/o problems. My Apex AD600A will read up to 3500kbit/s (above that it starts skipping and/or acting strange).

I've also found that the AD600A handles xVCDs MUCH better than xSVCDs. Don't know why...

[aldus4]

As my standalone plays 4.000kb/sec bitrated SVCD's it must be at least a 3x drive speed?

[Iview]

I believe the ability to read high bitrate has nothing to do with the spin speed of the drive. I think it's govern by the firmware and decoder program.
I have a Hitachi 505U which is a 2X drive but it reads xSVCD up to 5000k.
I also have a Sampo 620 with a 2X Actima drive, it only goes to 4000k. After I swapped a 12X drive in, it still won't go over 4000k without problem, and it is noisy.
So, this proves that the spin speed of the DVD drive has little to do with bitrate. Although 1X is too slow, 2X is certainly more than adequate for the average standalones. Probably that's why the standalone DVD manufacturers still stay with 2X drives instead of trying to keep pace with the PC DVD-ROM which is at 16X now (too noisy anyway).

[adam]

Iview: max bitrate is definitely determined by the speed at which the data can be read from the media. Its in the specs, you cant argue with the people who created the standards. Keep in mind those calculations are theoretical. The max bitrate for svcd is determined assuming that a 2x drive reads at exactly 2x. The hardware in your player might perform at higher speeds than this.

Yes of course firmware and the decoder effect your max bitrate but where do you think the specs for those come from? In terms of svcd playback everything is programmed according to the svcd standard (at least we should hope so) and the standard states that ultimately read speed is the determining factor.

Some players are more leniant that others, which explains why you can deviate so far from the standard using the original hardware. But you bring up a good point. Adding a faster loader (dvd-rom) won't always allow you to increase the bitrate because the maximum read speed for svcd is on paper and can't be changed without also changing the firmware and decoder.