1-pass vs 2-pass encoding at DVinfo.net

Taky Cheung · February 21st, 2008, 10:06 PM

With Adobe Media Encoder, if I'm encoding MPEG-2 DVD setting all minimum, average, and maximum bit rate to the same value, is it necessary to encode in 2-pass? Will 1-pass give the same result with such bit rate settings?

Craig Lieberman · February 22nd, 2008, 01:19 AM

I can't figure out how to adjust bit rate settings! What's the max bit rate setting you can get, anyway?

Trond Saetre · February 22nd, 2008, 01:32 AM

Quote:

Originally Posted by Craig Lieberman

I can't figure out how to adjust bit rate settings! What's the max bit rate setting you can get, anyway?

I'm not sure about the max possible bitrate, but I have great results with the following settings for the video:
(when using Dolby Digital 2.0 audio, set to 224kbps)
Max: 8,700kbps
Average: 8,400
Min: 7,300

In the media encoder window, in the lower right part, you will find the settings for video and audio quality.

Robert M Wright · February 22nd, 2008, 12:53 PM

Maximum bitrate for MPEG2 DVD video is 9800kbps. Maximum bitrate for DVD video and audio (combined bitrate) is 10080kbps. If you set minimum, average and maximum bitrates all the same, that's CBR (constant bitrate) and 2 pass encoding is pointless.

Taky Cheung · February 22nd, 2008, 01:00 PM

According to wikipedia, the maximun video+audio bitrate is 9.8mbps.

"DVD-Video discs have a raw bitrate of 11.08 Mbit/s, with a 1.0 Mbit/s overhead, leaving a payload bitrate of 10.08 Mbit/s. Of this, up to 3.36 megabits can be used for subtitles and a maximum of 9.80 megabits can be split amongst audio and video."

http://en.wikipedia.org/wiki/DVD-Video

Robert M Wright · February 22nd, 2008, 07:33 PM

I'm not sure how the numbers in the Wikipedia article were arrived at. This is the reference I used:

http://dvddemystified.com/dvdfaq.html

Taky Cheung · February 22nd, 2008, 07:41 PM

I take a look at the link you included. Somewhere in the middle, it said

"After system overhead, the maximum rate of combined elementary streams (audio + video + subpicture) is 10.08."

Robert M Wright · February 22nd, 2008, 08:36 PM

In section 3.4, it does say that the maximum bitrate for elementary streams combined is 10.08Mbps. In the same section they state that the maximum bitrate for video is 9.8Mbps. I have seen 9.8Mbps referred to as a maximum for video+audio on other sites. I think they might be confusing the 9.8Mbps maximum bitrate for video as being the maximum for video+audio. Of course, if you have subpictures, then audio+video would be lower than 10.08Mbps (by the bitrate for the subpictures).

I believe the 10.08Mbps total figure is correct, but I have not purchased a copy of the official DVD specifications from the DVD Forum (and don't intend to).

As a practical matter, I never set the maximum bitrate for video and audio combined to over 9.536Mbps (and have never used subpictures) anyway, and haven't had a problem thus far.

February 21st, 2008, 10:06 PM	#1
Taky Cheung Inner Circle Join Date: May 2007 Location: Los Angeles, USA Posts: 2,114	1-pass vs 2-pass encoding With Adobe Media Encoder, if I'm encoding MPEG-2 DVD setting all minimum, average, and maximum bit rate to the same value, is it necessary to encode in 2-pass? Will 1-pass give the same result with such bit rate settings?

February 22nd, 2008, 01:19 AM	#2
Craig Lieberman Regular Crew Join Date: Jan 2008 Location: Ladera Ranch, California Posts: 115	I can't figure out how to adjust bit rate settings! What's the max bit rate setting you can get, anyway?

February 22nd, 2008, 12:53 PM	#4
Robert M Wright Inner Circle Join Date: Jan 2006 Location: Minnesota (USA) Posts: 2,171	Maximum bitrate for MPEG2 DVD video is 9800kbps. Maximum bitrate for DVD video and audio (combined bitrate) is 10080kbps. If you set minimum, average and maximum bitrates all the same, that's CBR (constant bitrate) and 2 pass encoding is pointless.

February 22nd, 2008, 01:00 PM	#5
Taky Cheung Inner Circle Join Date: May 2007 Location: Los Angeles, USA Posts: 2,114	According to wikipedia, the maximun video+audio bitrate is 9.8mbps. "DVD-Video discs have a raw bitrate of 11.08 Mbit/s, with a 1.0 Mbit/s overhead, leaving a payload bitrate of 10.08 Mbit/s. Of this, up to 3.36 megabits can be used for subtitles and a maximum of 9.80 megabits can be split amongst audio and video." http://en.wikipedia.org/wiki/DVD-Video

February 22nd, 2008, 07:33 PM	#6
Robert M Wright Inner Circle Join Date: Jan 2006 Location: Minnesota (USA) Posts: 2,171	I'm not sure how the numbers in the Wikipedia article were arrived at. This is the reference I used: http://dvddemystified.com/dvdfaq.html

February 22nd, 2008, 07:41 PM	#7
Taky Cheung Inner Circle Join Date: May 2007 Location: Los Angeles, USA Posts: 2,114	I take a look at the link you included. Somewhere in the middle, it said "After system overhead, the maximum rate of combined elementary streams (audio + video + subpicture) is 10.08."

February 22nd, 2008, 08:36 PM	#8
Robert M Wright Inner Circle Join Date: Jan 2006 Location: Minnesota (USA) Posts: 2,171	In section 3.4, it does say that the maximum bitrate for elementary streams combined is 10.08Mbps. In the same section they state that the maximum bitrate for video is 9.8Mbps. I have seen 9.8Mbps referred to as a maximum for video+audio on other sites. I think they might be confusing the 9.8Mbps maximum bitrate for video as being the maximum for video+audio. Of course, if you have subpictures, then audio+video would be lower than 10.08Mbps (by the bitrate for the subpictures). I believe the 10.08Mbps total figure is correct, but I have not purchased a copy of the official DVD specifications from the DVD Forum (and don't intend to). As a practical matter, I never set the maximum bitrate for video and audio combined to over 9.536Mbps (and have never used subpictures) anyway, and haven't had a problem thus far.