dvd bitrate and compatibility

[mcpogue]

I have heard that one should keep maximum dvd bitrate at 8000kps or less for better compatibility and fewer playback problems (skips, freezes, etc.) This doesn't make sense to me because the dvd standard allows a max video bitrate of 9.8, 10.8 total and 8 max for multi-angle. All dvd players should be able to handle these specs for extended periods without problems. My question is: If the player is not at fault, is it a limitation of certain encoding/authoring apps, or a limitation of the physical media?

I know that recordable media is only a rough approximation of professionally pressed or stamped media. Is recordable media physically incapable of reproducing the maximums allowed by the dvd standard?

[junkmalle]

The DVD spec allows for those higher bitrates for PRESSED DVDs. Many of them have a harder time reading DVDR and DVDRW media because of the lower reflectivity.

[mcpogue]

So it is a limitation of the physical media?

I suppose also that it is difficult for most dvd writers to accurately cram such a dense high-bitrate track onto the disc?

[junkmalle]

It's not a limitation of the media it's a limitation of the lasers/sensors in the players. The optimal light wavelength for pressed DVDs and DVDR/RW is different.

[guns1inger]

If the disks are for sale to the public, and therefore to be played in a range of players that you have no control over, then err on the side of caution. I think 8000Kps is a little conservative. You should be able to use 8500 and a single AC3 audio track without problems.

If it is for your own use, push it as high as you can within the spec.

[mats.hogberg]

I suppose also that it is difficult for most dvd writers to accurately cram such a dense high-bitrate track onto the disc?

No, that's not correct. Bits and bytes are crammed equally tight no matter what bitrate used. Lower bitrate - more "head room" on the disc - higher bitrate just fill up the disc more (up to its max capacity). But where there is data on the disc, you can't tell if it's 1000 kbps or 8000 kbps just by "looking at" the data.

/Mats

[garryheather]

Don't forget that alternative soundtracks and subtitles are part of the stream - the more audio tracks you have for example, the less bandwidth you would have for the video. If you're making your own titles then chances are you're using 2 channel MPG audio or similar which doesn't eat into your available bitrate as much as say 5 channel or DTS does on commercial titles, or even worse, uncompressed PCM.

Therefore keeping your data rate below the maximum shouldn't be an issue for most people.

Don't forget also that most drives fitted into DVD players are not of the same speed as those supplied for data, ie predominantly PC, use. It is unlikely your standalone player has a 16x drive in it - even if it is badged as say a Lite-on who sell higher speed drives. It is likely not to have the same degree of error correction or buffering, so if you are going to ramp up the overall data rate it is worth considering the specs are there for a reason. They allow a little tolerance.