8000 cbr vs 6000 vbr

[ahfairley]

I hear a lot about the quality of TMPGEnc's 2-pass VBR encoding. But say I encode at a constant bit rate of 8000 instead of a 2-pass VBR of 8000 max 6000 avg, 2000 min. Won't that give equal or superior results to the the 2-pass method in less encoding time? (Size of encoded file is not an issue for me)

Thanks,

Alan

[SLK001]

If size is not an issue for you, then your method will probably result in a better video. But, if size is not an issue, I recommend going with a CBR of 9Mbps, which will almost guarantee you better results (at about 4GB per hour). If you use VBR encoding, set your upper limit to the limit (9600) instead of 8000.

[whytless physh]

"I recommend going with a CBR of 9Mbps, which will almost guarantee you better results"

Won't that run the risk of exceeding the maximum bit rate for a given DVD player? In theory, I know they should support a sustained transfer of 10mbps but how often do most units adhere to this? I'm not trying to argue you about this, I'm just curious.

[thxkid]

My Pansonic DMR-E20 records at the 1hr speed at 9800 and every DVD-R I have made has played in any DVD player without a problem and most of your Dual layered discs are hitting up into the 9000+ anyway, turn on your bps on your DVD player and just watch it during a movie see how often its up there, gotta use the dual layered discs, single layered will never go that high.

[SLK001]

First off, the maximum data rate for a DVD is 10.08Mbps, of which 9.8Mbps is the video max. With a video CBR of 9Mbps and one or two audio tracks at 384kbps, you won't exceed the spec. However, if you are using 1.5Mbps DTS audio, you'll have to lower your video BR.

Second, single layer or dual layer have nothing to do with the bits per second. There is absolutely no difference in the "bit rate" capability of the two. This is due entirely on the encoding process.

About the sustained data rates: All DVD players read data off the disk at a constant 26.16Mbps, which after demod results in a 13.08Mbps data stream fed into the read buffers. 2Mbps of this is error correction and 1Mbps is navigation data leaving 10.08Mbps of program data being feed into the program buffers. If the data is not used, it is simply discarded (for example, if your total data needs over a 1 second period was only 4Mbits, then the other 6.08Mbits would actually NOT be the program data you needed, so would be dumped). In short, a DVD that sustains a data rate at the max would be no problem for any player.

[whytless physh]

Well. That was enlightening. Thanks for the thorough reply.

[ahfairley]

Great reply SLK001! Query, if I encode my audio as PCM stereo (my for some reason my reciever doesn't seem to like MPEG layer 2) what would be the data rate for the PCM audio?

Thx

[SLK001]

For LPCM stereo audio, 384kbps will result in high quality sound (CD quality?).

For better space savings, 192kbps will result in very good quality.

For monaural audio, either 192kbps or 128kbps. NOTE: These are just the values I use... there are other bitrates that can be used.

[mol3000]

SLK001, is that a good video method that would fit on a 4.7 dvd r ??????

[SLK001]

SLK001, is that a good video method that would fit on a 4.7 dvd r ??????

What do you mean? What is it you are asking?

[mol3000]

sorry ..tht was kinda bland discription... .. i wanted to know if it would fit on a 4.7 g dvd-r

[SLK001]

To find out what bitrate you need to encode, use this formula:

(4.65Gbytes x 8bits/byte)/(YOUR_VID_LEN_MIN x 60sec/MIN)

For example, a 90 minute movie is:
(4.65G x 8)/(90 x 60) = 6.89Mbps

Subtract from the 6.89Mbps your audio rate (assume 384kbps) and you have a 6.5Mbps encoding rate (this is AVERAGE or CBR).

Notice that I used 4.65GB instead of 4.7GB. This is to allow for a menu or two and some "slack" ('tis better to be too short, than to be too long - trust me on this!).

[mol3000]

isnt there some kind of caculator or something that do that for u????

[jugernaut]

First off, the maximum data rate for a DVD is 10.08Mbps, of which 9.8Mbps is the video max. With a video CBR of 9Mbps and one or two audio tracks at 384kbps, you won't exceed the spec. However, if you are using 1.5Mbps DTS audio, you'll have to lower your video BR.

The 9.8 is the Video + Audio Max, if you use a 384 Mpeg track, you must sustract that from the 9.8 max. If you use more tracks you need to be a little more carefull.

[SLK001]

The 9.8 is the Video + Audio Max, if you use a 384 Mpeg track, you must sustract that from the 9.8 max. If you use more tracks you need to be a little more carefull.

Hey, Jugernaut,
The 9.8Mbps is really the max for the VIDEO portion of your DVD. The TOTAL MAXIMUM rate (including everyting on your DVD) really is 10.08Mbps. A good source of info on these specs is Jim Taylor's "DVD Demystified".