Format                                   : MPEG-4 Visual

Format profile                           : Advanced Simple@L5

Format settings, BVOP                    : 2

Format settings, QPel                    : No

Format settings, GMC                     : 3 warppoints

Format settings, Matrix                  : Default (H.263)

Muxing mode                              : Packed bitstream

Codec ID                                 : XVID

Codec ID/Hint                            : XviD

Duration                                 : 24mn 49s

Bit rate                                 : 833 Kbps

Width                                    : 704 pixels

Height                                   : 396 pixels

Display aspect ratio                     : 16:9

Frame rate                               : 23.976 fps

Color space                              : YUV

Chroma subsampling                       : 4:2:0

Bit depth                                : 8 bits

Scan type                                : Progressive

Compression mode                         : Lossy

Bits/(Pixel*Frame)                       : 0.125

Stream size                              : 148 MiB (86%)

Writing library                          : XviD 1.2.1 (UTC 2008-12-04)

mono MPEG4ModifierMod.1.4.4.exe

Survival guide for standalone mpeg4 player

1.Standalone mpeg4 player

So you got a new shiny "divx" certified standalone dvd player but have problems with it. This small doc tries to help you make it play your videos.

2.The packed vop hack

B frames are nice but they induce a one frame delay shift because a b frame needs both its previous and next I/P frames to be decoded.

That does not cope very well with VFW (video for windows) limitation that more or less assume one frame in/ one frame out.

To workaround this, DivxNetork introduced PB frame in avi. To explain it see the b-frame doc.

Basically they add a non coded image (N-vop) after an frame containing both a P and a B frame. Some (most?) players choke or stutter on that as it creates artificially additionnal frame. To detect that, they put also a specific marker in the user data section of the mpeg4 stream. Some players use that information to switch to packed vop mode, but it is not 100% reliable. Plus the stream is not 100% iso compliant.

Rule #1 : Dont use packed frames. With avidemux you can't but with some other software you can.
Rule #2 : If you have some, depack them.
In order to do so, when prompted if avidemux should depack such frame, say yes. Avidemux will take each frame and scan for more than one vop inside it. If it finds several it re-creates separate frames and destroy the corresponding N-vop frames.

That will take care of the packed vop, but the marker in user data will remain. to also remove it, use save unpacked vop instead of the usual save video.

That will scan and fix on the fly the marker so that the stream are detected as non packed stream.

That should solve all Divx packed file, but may not work for some xvid files.

Warning: If the file has VBR audio, don't forget to do a Misc/Build VBR map after loading it.

If you have a huge amount of such files to convert you can use a script like:

#!/bin/bash

export SRC=/tmp/fma2

export TGT=/tmp/fma3

perl foreach.pl $SRC/*.avi "avidemux2 --force-unpack  --load $SRC/%f  --audio-map  --save-unpacked-vop $TGT/fixed_%f --quit"

3.GMC and Qpel

Xvid and lavcodec can use more complete GMC (global motion compensation) and Qpel (Quarter Pixel) models than divx codec.

With those, you are screwed and need to re-encode the video

That means dual-pass encoding to keep the same size.

There is a way to get almost the same result using only one pass.

Assuming your video is correctly done, the previous encoding already distributed quantizers and bitrate to get a good quality for a given size.

Why not reuse that information ?

To do so, set xvid (or lavcodec) to use Follow mode. In that mode, they will encode each frame with the quantizer used previously to encode it.

The result will have about the same size/quality compared to the original but using only one pass.

That can be done using cli mode also to process plenty of files in a row :

#!/bin/bash

export SRC=/tmp/fma2

export TGT=/tmp/fma3

perl foreach.pl $SRC/*.avi "avidemux2 --force-unpack  --load $SRC/%f  --audio-map  --video-process --video-codec xvid4  --video-conf follow=1000  --save $TGT/fixed_%f --quit"

4.Muxing

I have found that some software (like some version of nandub) does not mux properly the file. That makes standalone stutters and freeze. The fix is simple : just load and save the file in avidemux2