[XviD-devel] Questions / Bug fixes / Patches

[Carl Eric Codere]

>Hi Carl,

>> F:\movies\outputs>..\tools\mp4box\MP4Box -fps 29.970 -nodrop -packed  
>>  -new -add .\sherlock_intro_qvga_Xvid_L6.m4v

>why are you using "-packed" with MP4Box? Are you sure your input file is
>a packed bitstream? I suppose the "-packed" option might be the reason
>why the N_VOPs get stripped and the stream is converted to variable
>framerate. Could you try without "-packed"?

>> Information on the assertion error (I was encoding from virtualdub >1.9.9):
>> mbcoding.c : line 595:
>> estimated_length == coded_length

>This assert is nothing to worry about. In fact, it got already removed
>in the latest dev version of xvid.

>Best regards,
>Michael
> 

Greetings,
        Sorry, the mp4box parameters I sent you yesterday were 
added because I was debugging to try to resolve the problem, 
here is other trials I did when I encoded with an unpatched version 
of Xvid, the resulting file did have the N-VOP frames. As you can see 
I use mencoder to extract the raw MP4 stream, I then try to create a MP4 usingvmp4box.


F:\movies\outputs>..\tools\MPlayer-rtm-svn-31878\mencoder.exe sherlock_intro_qvg
a_Xvid.avi -o .\sherlock_intro_qvga_Xvid.m4v -of rawvideo -nosound -ovc copy
MEncoder Sherpya-SVN-r31878-4.2.5 (C) 2000-2010 MPlayer Team
159 audio & 347 video codecs
success: format: 0  data: 0x0 - 0x269822
AVI file format detected.
[aviheader] Video stream found, -vid 0
[aviheader] Audio stream found, -aid 1
VIDEO:  [XVID]  320x240  24bpp  29.970 fps  289.9 kbps (35.4 kbyte/s)
[V] filefmt:3  fourcc:0x44495658  size:320x240  fps:29.970  ftime:=0.0334
videocodec: framecopy (320x240 24bpp fourcc=44495658)
Pos:  40.8s   1224f (99%)  0.00fps Trem:   0min   1mb  A-V:0.000 [289:0]

Video stream:  289.915 kbit/s  (36239 B/s)  size: 1480046 bytes  40.841 secs  12
24 frames

F:\movies\outputs>..\tools\mp4box\MP4Box -fps 29.970 -new -add .\sherlock_intro_
qvga_Xvid.m4v .\sherlock_intro_qvga_Xvid_256_Xvid.mp4
MPEG-4 Video import - 320 x 240 @ 29.9700 FPS
Indicated Profile: Simple Profile @ Level 3
Import results: 1196 VOPs (6 Is - 1190 Ps)
import using Variable Frame Rate - Removed 28 N-VOPs
Converting to ISMA Audio-Video MP4 file...
Saving .\sherlock_intro_qvga_Xvid_256_Xvid.mp4: 0.500 secs Interleaving



F:\movies\outputs>..\tools\MPlayer-rtm-svn-31878\mencoder.exe sherlock_intro_qvg
a_Xvid.avi -o .\sherlock_intro_qvga_Xvid.m4v -of rawvideo -nosound -ovc copy
MEncoder Sherpya-SVN-r31878-4.2.5 (C) 2000-2010 MPlayer Team
159 audio & 347 video codecs
success: format: 0  data: 0x0 - 0x269822
AVI file format detected.
[aviheader] Video stream found, -vid 0
[aviheader] Audio stream found, -aid 1
VIDEO:  [XVID]  320x240  24bpp  29.970 fps  289.9 kbps (35.4 kbyte/s)
[V] filefmt:3  fourcc:0x44495658  size:320x240  fps:29.970  ftime:=0.0334
videocodec: framecopy (320x240 24bpp fourcc=44495658)
Pos:  40.8s   1224f (99%)  0.00fps Trem:   0min   1mb  A-V:0.000 [289:0]

Video stream:  289.915 kbit/s  (36239 B/s)  size: 1480046 bytes  40.841 secs  12
24 frames

F:\movies\outputs>..\tools\mp4box\MP4Box -fps 29.970 -new -nodrop -add .\sherloc
k_intro_qvga_Xvid.m4v .\sherlock_intro_qvga_Xvid_256_Xvid.mp4
MPEG-4 Video import - 320 x 240 @ 29.9700 FPS
Indicated Profile: Simple Profile @ Level 3
Import results: 1224 VOPs (6 Is - 1218 Ps)
Removed 28 N-VOPs
Converting to ISMA Audio-Video MP4 file...
Saving .\sherlock_intro_qvga_Xvid_256_Xvid.mp4: 0.500 secs Interleaving


p.s: Furthermore, I am really sorry if it is not an appropriate 
to ask here, but Ihave a question regarding max. bitrate of 
MPEG-4 Part/2 for different profiles and levels. I have noticed, 
that for example if I configure the vfw codec to SP at L3 and I set the 
bitrate to 384 kbps (the max.) in 2-pass mode, this indicates the overall bitrate of the stream, am I correct? After importing to mp4box (with my patched version of xvid),the MP4 stream indicates a max. bitrate that can go above the allowed Max. bitrate of 384 kbps for that level, is that correct? Is this still respecting the standard? From what I seem to understand by reading, and correct me if I am wrong, the max. bitrate parameter of the standard is an overall bitrate, and not the instant bitrate for a VOL? I am telling you this because I checked the code a bit and found a function check_curve_for_vbv_compliancy() in plugin_2pass2.c that returns VBV_PEAKRATE if the vbv_peakrate is above 0, which is not the case for ISO profiles (as seen in config.c of the vfw driver). 

I have been trying to understand the max. bitrates for quite a while now, and am trying to  encode my videos to adhere strictly to the ISO standards... 

Best regards,
Carl