Bitrate question and two pass question

[cyberlion]

General
 Complete name                    : G:\21.avi
 Format                           : AVI
 Format/Info                      : Audio Video Interleave
 File size                        : 700 MiB
 Duration                         : 1h 57mn
 Overall bit rate                 : 832 Kbps
 Writing application              : VirtualDubMod 1.5.10.2 (build 2540/release)
 Writing library                  : VirtualDubMod build 2540/release
 
 Video
 ID                               : 0
 Format                           : MPEG-4 Visual
 Format settings, BVOP            : Yes
 Format settings, QPel            : No
 Format settings, GMC             : No warppoints
 Format settings, Matrix          : Default (H.263)
 Muxing mode                      : Packed bitstream
 Codec ID                         : DX50
 Codec ID/Hint                    : DivX 5
 Duration                         : 1h 57mn
 Bit rate                         : 713 Kbps
 Width                            : 608 pixels
 Height                           : 336 pixels
 Display aspect ratio             : 16:9
 Frame rate                       : 25.000 fps
 Color space                      : YUV
 Chroma subsampling               : 4:2:0
 Bit depth                        : 8 bits
 Scan type                        : Progressive
 Bits/(Pixel*Frame)               : 0.140
 Stream size                      : 600 MiB (86%)
 Writing library                  : DivX 6.8.0 (UTC 2007-12-04)
 
 Audio
 ID                               : 1
 Format                           : MPEG Audio
 Format version                   : Version 1
 Format profile                   : Layer 3
 Mode                             : Joint stereo
 Mode extension                   : MS Stereo
 Codec ID                         : 55
 Codec ID/Hint                    : MP3
 Duration                         : 1h 57mn
 Bit rate mode                    : Constant
 Bit rate                         : 112 Kbps
 Channel(s)                       : 2 channels
 Sampling rate                    : 44.1 KHz
 Stream size                      : 94.3 MiB (13%)
 Alignment                        : Split accross interleaves
 Interleave, duration             : 80 ms (2.00 video frames)
 Interleave, preload duration     : 500 ms
 Writing library                  : LAME3.97 
 Encoding settings                : -m j -V 4 -q 2 -lowpass 15.6 -b 112
 Language                         : English

How was the File Size was determined. I can't calculate properly with file size = (video bitrate + audio bitrate) * running time

Also, what is difference between Two Pass- 1st pas and Two Pass - 2nd Pass, as such i want to make movie within file size and quality is very important, no problem if more CPU and time is used.

[Case]

How was the File Size was determined. I can't calculate properly with file size = (video bitrate + audio bitrate) * running time

Duration: 1h 57mn = 117 min = 7020 seconds (+/- 59 seconds)
Audio bitrate: 112 Kbps (CBR); 112 * 7020 = 786,240 kilobits = 98,280 kilobyte = 95.98 MB. Pretty close to the reported 94.3 MiB.
Video bitrate: 713 Kbps (VBR?); 713 * 7020 = 5,005,260 kilobits = 625,657.5 kiliobyte = 611 MB. Not too far off from the reported 600 MiB.
Overall bit rate: 832 Kbps; 832 * 7020 = ... = 713 MB. Not too far off from the reported 700 MiB.
The differences come from the fact that the encoder uses variable bitrate, so you won't know the actual size until the encoding is done, no matter what target bitrate you specify.

[jagabo]

video bitrate = 713 kbps
audio bitrate = 112 kbps
running time = 7020 seconds (117 minutes)

(713 + 112) * 7020 = 5,791,500 kbits

divide by 8 to get kbytes

5791500 / 8 ~= 723938 kbytes or 723,938,000 bytes

But all those numbers are decimal. MiB is based on 1024*1024, not 1000*1000. So take the number of bytes and divide by 1024 twice:

723,938,000 / 1024 / 1024 = 690 MiB.

Adding a little overhead for the AVI container to bring the full size to 700 MiB, as reported by MediaInfo. Use a bitrate calculator program to take care all those calculations for you.

During the first pass of a two pass encode the codec is examining the video to see how much relative bitrate each frame needs. During the second pass it uses that information to distribute bitrate to deliver the best quality for the desired average bitrate. Ie, frames that need more bitrate get more bitrate, frames that need less get less, in the end the requested average bitrate is achieved (and hence the expected file size).

[PuzZLeR]

Good work guys, and I will add to this:

Also, what is difference between Two Pass- 1st pas and Two Pass - 2nd Pass, as such i want to make movie within file size and quality is very important, no problem if more CPU and time is used.

Since the encoder doesn't know in advance until it "sees" the entire movie first it will do one pass to gather information. Then on the second pass it allocates the bitrate to what it believes are scenes that need it most such as more bitrate to complex scenes (like motion) and less to more simple scenes.

Since, in theory, it works with a finite amount of bitrate (the file size limit you give it), it will attempt to give you the best quality at that size.

This is why you shouldn't use something like CBR (Constant Bitrate) for video, which is one pass (especially since you don't care about CPU time). This method will give the exact amount of bitrate for every scene, but will likely give too little for complex scenes and too much for simple scenes. Same file size, but less quality. You save one pass, but the result is not efficient.

Since you mention that quality is important to you, let me suggest Constant Quality mode if your encoder supports it, which is what the more experienced encoders here seem to like.

This works the opposite - ask it the quality you want and it decides the minimum bitrate at the end. Since, in theory, it works with an infinite amount of bitrate (no file size limit restrictions), it will scan through the entire movie - in only one pass - and give this appropriate minimum bitrate for each scene.

It doesn't guarantee you a file size but guarantees you the quality.

[cyberlion]

I actually want quality in minimal size with more CPU and time usage.

x264 or Xvid, which is globally accepted.

If I make an 700 MB Xvid, will it same quality in x264 in 350 MB

[PuzZLeR]

I actually want quality in minimal size with more CPU and time usage. x264 or Xvid, which is globally accepted.

Although you won't know the file size till after the encode, Constant Quality (CFR in x264 and CQ in Xvid) will give you the minimum file size at the quality you ask it. It will not bloat your file.

But, if you want an exact file size, and highest quality, then go ahead and use 2 pass at the slower settings (such as Slower, Very Slow, Placebo with x264). And if you want max quality when using bitrate encoding for your end result, then just avoid CBR (also called ABR)

If I make an 700 MB Xvid, will it same quality in x264 in 350 MB

It depends but likely not. Yes, x264 has better compression than Xvid, especially at the lower bitrates, but I doubt twice as much. I would say 450MB-550MB might be a better answer.

Actually, using a similar Constant Quality setting with both, Xvid and x264, will shed light on an answer as to what each yields in file size with respect to the Source. But every Source will be different.

[cyberlion]

So which is better, confused between Xvid and x264, on top of that i know Xvid, Which format Xvid or x264 is accepted by all systems and run freely.

I can only do simple maths like you guys. Is there no program, where the movie file gets loaded and I put only my size limit and it shows Video Bit-Rate. It is head ache to learn each movie length act through it.

Also what does Target size and Target bitrate mean in Xvid configuration of Vdub of two passes.

[davexnet]

Target size means it will manipulate the bitrate/quality to provide a size of the video that you specify.
Target bitrate means it will manipulate the "quality" to provide the average bitrate you specify.

In both cases, since it's two-pass, bit's are allocated on demand; eg. high action scenes get more bits.

[PuzZLeR]

So which is better, confused between Xvid and x264, on top of that i know Xvid, Which format Xvid or x264 is accepted by all systems and run freely.

Depends.

If you're looking at less encoding time and better compatibility among DvD and blu-ray players, particularly those with certification (like DivX), then Xvid is "better"

If you're looking at better compression (less file size per quality level) then x264 is "better".

However, x264's compatibility is still expanding and highly dependent on profile (QuickTime, iPod, PS3, blu-ray, DXVA, etc.) If you don't want to fiddle with profiles, but want it to "just play" outside of your PC, then you would need to look into a media box for this format.

[cyberlion]

I did this setup and still it had gone to 1.67 GB

General
Complete name : C:\Users\IREG\Desktop\21-3.avi
Format : AVI
Format/Info : Audio Video Interleave
File size : 1.67 GiB
Duration : 1h 57mn
Overall bit rate : 2 037 Kbps
Writing application : VirtualDubMod 1.5.10.2 (build 2540/release)
Writing library : VirtualDub build 32817/release

Video
ID : 0
Format : MPEG-4 Visual
Format profile : Simple@L3
Format settings, BVOP : No
Format settings, QPel : No
Format settings, GMC : No warppoints
Format settings, Matrix : Default (H.263)
Codec ID : XVID
Codec ID/Hint : XviD
Duration : 1h 57mn
Bit rate : 1 915 Kbps
Width : 608 pixels
Height : 336 pixels
Display aspect ratio : 16:9
Frame rate : 25.000 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.375
Stream size : 1.57 GiB (94%)
Writing library : XviD 1.2.1 (UTC 2008-12-04)

Audio
ID : 1
Format : MPEG Audio
Format version : Version 1
Format profile : Layer 3
Mode : Joint stereo
Mode extension : MS Stereo
Codec ID : 55
Codec ID/Hint : MP3
Duration : 1h 57mn
Bit rate mode : Constant
Bit rate : 112 Kbps
Channel(s) : 2 channels
Sampling rate : 44.1 KHz
Stream size : 94.3 MiB (5%)
Alignment : Split accross interleaves
Interleave, duration : 40 ms (1.00 video frame)
Interleave, preload duration : 500 ms
Writing library : LAME3.97
Encoding settings : -m j -V 4 -q 2 -lowpass 15.6 -b 112

My BitRate Settings never end up - properly, after putting only Target bitrate in Xvid Config, it goes double the size. I have turned on deblocking and deriling in Xvid decoder option.


How can i turn on BOVP.

[jagabo]

Why do you have FPS set to 15? Your video is 25 fps. Did you run the first pass and the second pass with the same settings?

[cyberlion]

Are there different settings for both pass. I just calculated Xvid configuration to get that. Its not at all, acting to the settings, is there any variable change happening to settings to give quality.

Though I have seen in two passes, the movie is run two times i think, my go in one line and closes after the process is over in 16 min. Really don't know whether VDub did it with two passes,.

[jagabo]

To do a 2-pass compression in VirtualDub you set everything up (open video file, set filters, etc) and set Xvid to "Twopass - 1st pass" and select any other Xvid options you want. Then select File -> Save as AVI. During the first pass Xvid is only examining the video, the file that's created will only have black frames. Once that is done you go back to the Xvid config dialog and change it to "Twopass - 2nd pass", select the desired size or bitrate (don't change any other VirtualDub settings), then File -> Save as AVI again. This time Xvid will produce an output file with your video.

[cyberlion]

So Is there no provision, that it works one after other, I have to intervene in between when 1st pass over.

[jagabo]

So Is there no provision, that it works one after other, I have to intervene in between when 1st pass over.

You can use VirtualDub's batch processing to perform the two passes. The setup procedure is the same, but instead of File -> Save as AVI you select File -> Queue Batch Operation -> Save as AVI. You do that for both passes then start up the batch processor to perform the two passes with File -> Job Control.

[davexnet]

A second option is Avidemux. It does both passes automatically - although I found it to be a little slower than Vdub.

[jagabo]

I find AviDemux to be pretty unreliable overall. Many crashes, aborts, lockups, etc.

[davexnet]

You are right about the somewhat unpredictable nature of Avidemux.
I had version 253 installed, and decided to update to one of the more recent SVN builds.

The newer release crashed when handling the ac3 audio on a file I had previously processed without problems (on the older
release). Reinstalled the older release and back in business. These kinds of problems plague this product for some reason.

I've found the 253 release version to work reasonably well.