Minimum bitrate for VCDs

[Simon_Haddad]

Does anyone know the minimum video bitrate you can use to encode a compliant VCD

I know the maximum (1151929.1 bits/sec).

[MOVIEGEEK]

It depends on your encoder(Ulead min. is 434kbps,TMPGEnc is 1kbps),player(a PC will play 1kbps,a DVD player 600?) and your taste in video quality(anything under 900kbps looks like crap to me).

[Heavensent]

in vcd you cant change the bitrate, it has a fixed bitrate of 1150,
anything ealse is xvcd and might not play on all players.

[Simon_Haddad]

MOVIEGEEK,
I'm only interested in bitrates that are compliant with the VideoCD 1.1 and 2.0 standards, I'm sure 1kbps isn't in that range.

Heavensent,
I'm not using a variable bitrate like an svcd, I'm still going to use a constant bitrate (fixed bitrate), as per the VCD standard.

So, what's the legal range of constant video bitrates in the VideoCD 1.1 and 2.0 standards?

__________ kbps - 1151.9291 kbps

[flaninacupboard]

simon, it's not flexible. 1150 is VCD bitrate. that's it. most players don;t have a problem playing anything lower (and in a lot of cases, anything higher) but as heavensent said, it becomes an XVCD.

[hwoodwar]

Simon_Haddad:

There is no "legal range" for Video Bitrate and VCD compliance. There is one, and only one value allowed to be totally compliant, a Constant Bitrate of 1150kbits/sec.

[pibble]

I think they're trying to say that a true VCD has fixed bitrate of exactly 1150 kbit/s. Anything else is not a "true" VCD and may not be playable in all players out there. Of course, almost every new player sold these days can play these nonstandard CBR VCD's at varying (fixed) bitrates. As far as your original question -- if you are violating the standard by not using 1150 kbit/s, there is not neccesarily a "minimum" bitrate other than what you think looks acceptable with your material, and what you think will be handleable by the players out there that you are targeting. My advice: if you want a VCD, stick to 1150 kbit/s. If you want to fool around with xVCD, realize you are not producing a standards compliant disc.

[Simon_Haddad]

I have come across capturing and editing software that use other bitrates for encoding VideoCD. ATI TV 7.1 records directly to VideoCD format with a constant video bitrate of 1040 kbps. Ulead Videostudio 4.0 encodes VideoCD at 1123 Kbps. If the definition of compliant VideoCD is as rigid and narrow as you all say, then

1. The authorities would refer to 1151929.1 bits/sec as the only bitrate instead of the maximum bitrate ( vcd_on_cdi_41.pdf, page 21, by Royal Philips Electronics NV and ICDIA), and

2. Everyone but me would be burning XVCDs, as I appear to be the only one encoding at 1151929.1 bits/sec.

[txpharoah]

Many players, as well as the MPEG1 DVD standard, consider 1150k-1856k at the acceptable range for bitrates on 352x240 MPEG1 VCD-spec video. The 1856 is MUCH better than 1150, and I have YET to find a player that will reject a 1856k disc when it also palys a 1150k disc. Other specs, above and below, fall into the XVCD 'standard' and are not compatible with many players. Some software also considers 1856k to be an MPEG1 VCD spec encode.

[adam]

~1856kbits is the maximum for mpeg1 in the DVD standard. That has nothing to do with the VCD standard. The VCD standard is actually quite clear, the max is around 1150kbits. This number is derived from the theoretical max speed that data can be read off of a 1x drive. There is probably no VCD player in existence which could properly play a VCD encoded at a bitrate that high, though most DVD players are of course more leniant. Still, I have run across numerous VCD compliant DVD players who cannot properly play a VCD with a bitrate much higher than 1150kbits.

Looking through the IEC specs, I see no mention of any minimum bitrate required for VCD. I only see a max so I suppose you can go as low as you want as long as its encoded in CBR.

As far as differences in output bitrate from one program to the next, the fact is that there is no such thing as true CBR. Mpeg encoding by definition requires fluctuation of bitrate. CBR is just supposed to mean that the bitrate always averages out to the same number every GOP, but within that GOP the bitrate is still being adjusted according to the type of frame, ie: I,P, or B, as well as according to its complexity. It is very common to get an average slightly lower than what you set when encoding in CBR and that is why some encoders allow you to pad the stream with null data, to ensure that you do not fall short of your set average bitrate.

Also if you are outputting program streams (mpg) than there are other factors which can affect the output size, and give the appearance of a higher bitrate if you are just doing the math to calculate your bitrate.

Also take any software bitrate calculations with a grain of salt. No program is perfect, and with bitrate calculators there is always going to be a margin of error.

[RoopeT]

The 1856 is MUCH better than 1150, and I have YET to find a player that will reject a 1856k disc when it also palys a 1150k disc

Try any Philips DVD player (at least my DVD 622 doesn't play anything over 1150, haven't tried yet my DVDR980 as I have no interest making any kind of VCD ever). This is only for CD media, if I burn mpeg1 @ 1850 kbps onto DVD media there's no problem.

[vitualis]

VCD is dependent on the 1x CD speed. 1150 kbit/s is the max for the video, though I think that a lower bitrate will still play okay as long as you pad the stream so that 1 sec of video = 1 sec on the CD.

Of course, this eliminates the advantage in using a lower bitrates...

My stand-alone VCD player cannot handle any XVCD with a higher or lower bitrate. If it is higher, it will lead to skips. If it is lower, it leads to skips (with the video playing too fast).

Regards.

[RoopeT]

I have no problems playing SVCDs, so for Philips DVD players the reason why the player doesn't play XVCDs with a higher bitrate lies elsewhere (firmware?)

[vcd4ever]

Simon_Haddad,

The maximum bitrate for a standard vcd is defined in the whitebook spec, and the whitebook spec clearly states that the maximum bitrate is 1150. The maximum bitrate was later changed to 1151929.1 because all vcd players that are strictly compliant to the whitebook spec also plays a standard vcd with a maximum bitrate of 1151929.1 without any problems. The minimum bitrate allowed for a standard vcd is something that i haven't seen defined in any spec and the reason for this is most likely because the mpeg file according to the whitebook spec must have a system muxrate of 1411200 bits/sec. The minimum bitrate can therefore be whatever you want to use because the system stream must be padded to 1411200 for it to be standard vcd compliant according to the whitebook spec.

vcd4ever.

[MOVIEGEEK]

@Simon_Haddad,
After doing some reading on other sites the answer to your original question of "minimum video bitrate" is there is none.
If you want your VCD's to be able to play on all VCD compatible DVD players stick with 1151kbps.