[XviD-devel] Questions / Bug fixes / Patches

Thu Nov 25 07:33:39 CET 2010

Are you sure your method of testing directshow filters is accurate? I don't think simply counting the number of output frames is sufficient, maybe the filter is displaying the previous frame for a longer period of time (which IMHO would be valid behaviour).

> Date: Wed, 24 Nov 2010 23:52:40 -0500
> From: cecodere at yahoo.ca
> To: xvid-devel at xvid.org
> Subject: Re: [XviD-devel] Questions / Bug fixes / Patches
> 
> On 2010-11-24 06:46, Michael Militzer wrote:
> > Carl,
> >
> > I have applied the frame_drop_ratio patch to CVS. When frame_drop_ratio is
> > set to "0", no N_VOPs will now be produced anymore by xvidcore. Hopefully,
> > this will workaround the issues you observed with MP4Box muxed .mp4 files.
> >
> > I have to admit however that I'm still confused: If I recall correctly
> > we concluded last time when this topic was discussed that MP4Box appears
> > to rewrite N_VOPs as P_VOPs with all Skip-MBs upon muxing a xvid encoded
> > stream into .mp4 files using the -nodrop option. Your most recent post
> > however seems to indicate that the N_VOPs are preserved by MP4Box for
> > -nodrop. Has MP4Box behavior changed?
> >
> > Best regards,
> > Michael
> 
> Greetings,
> You are right, but maybe it was because I did a wrong 
> manipulation, or the stream was packed? Now I have been very careful to 
> do some accurate tests. Here is some further analysis on the issues I 
> have encountered. I have used Mencoder to encode the same file which 
> contains 1176 frames The main difference is the xvid level (Mencoder 
> has the same patch as i submitted to you) and the packed stream indicator.
> 
> The conclusions I see is as follows:
> 
> - When B-frames are disabled (Such as in Simple Profile), packed 
> bitstream for those profiles is not supported at all. See TEST 4, and 
> even in VFW the packed bitstream option is disabled. Because of this non 
> packed bitstream N-VOPs are inserted, is that actually logical and allowed?
> 
> - A lot of the decoders (see end of the analysis) are not frame accurate
> and do not consider the N-VOPs accurately, this seems to even be the 
> case of the Xvid Directshow filter(?).
> 
> 
> - When I run MP4Box on TEST 4, with the following options:
> 
> 
> mp4box -nodrop -new -add %2_%bitRateHigh%_MP4 at SP_Xvid_packed.avi 
> %2_MP4 at SP_%bitRateHigh%_Xvid_packed_nodrop.mp4
> 
> MP4Box gives the following result :
> 
> AVI XVID video import - 320 x 240 @ 29.9700 FPS - 1176 Frames
> Indicated Profile: ISO Reserved Profile
> Import results: 1176 VOPs (6 Is - 1170 Ps)
> Stream has 27 N-VOPs
> Converting to ISMA Audio-Video MP4 file...
> Saving 
> C:\video\testsuite\xvidtests\sherlock_qvga at 30fps_MP4@SP_768k_Xvid_packed_nodrop.mp4: 
> 0.500 secs Interleaving
> 
> GSpot then indicates that the resulting MP4 has DF N-VOPs as P-VOPs. 
> 1176 frames total.
> 
> 
> MP4Box gives the following result :
> 
> mp4box -new -add %2_%bitRateHigh%_MP4 at SP_Xvid_packed.avi 
> %2_MP4 at SP_%bitRateHigh%_Xvid_packed.mp4
> 
> AVI XVID video import - 320 x 240 @ 29.9700 FPS - 1176 Frames
> Indicated Profile: ISO Reserved Profile
> Import results: 1149 VOPs (6 Is - 1143 Ps)
> import using Variable Frame Rate - Removed 27 N-VOPs
> Converting to ISMA Audio-Video MP4 file...
> Saving 
> C:\video\testsuite\xvidtests\sherlock_qvga at 30fps_MP4@SP_768k_Xvid_packed.mp4: 
> 0.500 secs Interleaving
> 
> 
> GSpot then indicates that the resulting MP4 has only P-VOP, but only 
> 1,149 frames, so 27 frames have been removed.
> 
> 
> The four encoding tests I used:
> 
> TEST 1 =============================================
> sherlock_qvga at 30fps_768k_MP4@ASP_DivX_Xvid.avi
> Mencoder options:
> bitrate=768
> profile=asp5
> me_quality=6
> trellis
> vhq=1
> min_iquant=2
> min_pquant=2
> min_bquant=2
> frame_drop_ratio=0
> nopacked
> par=vga11
> max_bframes=2
> MPEG4Modifier analysis on output file:
> Packed bitstream: No
> QPel: No
> GMC: No
> Interlaced: No
> Aspect ratio: Square pixels
> Quant type: H.263
> FourCC: XVID
> User data: XviD0050
> 
> I-VOPs: 6 (0,51%)
> P-VOPs: 453 (38,52%)
> B-VOPs: 717 (60,97%)
> S-VOPs: 0 (0,00%)
> N-VOPs: 0 (0,00%)
> 
> Max consecutive B-VOPs: 2
> 1 consec: 41,02%
> 2 consec: 58,98%
> 
> 
> TEST 2 =============================================
> sherlock_qvga at 30fps_768k_MP4@ASP_DivX_Xvid_packed.avi
> Mencoder options:
> bitrate=768
> profile=asp5
> me_quality=6
> trellis
> vhq=1
> min_iquant=2
> min_pquant=2
> min_bquant=2
> frame_drop_ratio=0
> packed
> par=vga11
> max_bframes=2
> MPEG4Modifier analysis on output file:
> Packed bitstream: Yes
> QPel: No
> GMC: No
> Interlaced: No
> Aspect ratio: Square pixels
> Quant type: H.263
> FourCC: XVID
> User data: DivX503b1393p
> XviD0050
> 
> I-VOPs: 6 (0,51%)
> P-VOPs: 453 (38,52%)
> B-VOPs: 717 (60,97%)
> S-VOPs: 0 (0,00%)
> N-VOPs: 0 (0,00%)
> 
> Max consecutive B-VOPs: 2
> 1 consec: 41,02%
> 2 consec: 58,98%
> 
> 
> 
> TEST 3 =============================================
> sherlock_qvga at 30fps_768k_MP4@SP_Xvid.avi
> Mencoder options:
> bitrate=768
> me_quality=6
> trellis
> vhq=1
> min_iquant=2
> min_pquant=2
> min_bquant=2
> frame_drop_ratio=0
> nopacked
> par=vga11
> profile=sp4a
> MPEG4Modifier analysis on output file:
> Packed bitstream: No
> QPel: No
> GMC: No
> Interlaced: No
> Aspect ratio: Square pixels
> Quant type: H.263
> FourCC: XVID
> User data: XviD0050
> 
> I-VOPs: 6 (0,51%)
> P-VOPs: 1143 (97,19%)
> B-VOPs: 0 (0,00%)
> S-VOPs: 0 (0,00%)
> N-VOPs: 27 (2,30%)
> 
> 
> TEST 4 =============================================
> sherlock_qvga at 30fps_768k_MP4@SP_Xvid_packed.avi
> Mencoder options:
> bitrate=768
> me_quality=6
> trellis
> vhq=1
> min_iquant=2
> min_pquant=2
> min_bquant=2
> frame_drop_ratio=0
> packed
> par=vga11
> profile=sp4a
> MPEG4Modifier analysis on output file:
> Packed bitstream: No
> QPel: No
> GMC: No
> Interlaced: No
> Aspect ratio: Square pixels
> Quant type: H.263
> FourCC: XVID
> User data: XviD0050
> 
> I-VOPs: 6 (0,51%)
> P-VOPs: 1143 (97,19%)
> B-VOPs: 0 (0,00%)
> S-VOPs: 0 (0,00%)
> N-VOPs: 27 (2,30%)
> 
> 
> 
> CODEC TESTS (using GraphStudio)
> -------------------------------
> 
> These tests check the video output of the different DirectShow filters 
> tested, on
> the MP4 generated by TEST 4 (With the 27 N-VOP frames in the MP4 Stream).
> 
> -> 3IVX 5.0.2
> -> DivX 6.8.5
> -> Xvid 1.2.2
> -> FFDSHOW tryouts 3530 (August 2010)
> 
> 
> 
> 1) MPC MP4 Splitter -> FFDSHOW -> Monograph FRAME Grabber (YUV Sequence)
> 
> Generated YUV (I420 file size): 132 364 800.
> 1149 Frames grabbed (NOK!)
> 
> 2) 3IVX MPEG-4 Splitter -> 3IVX Video Decoder -> Monograph FRAME Grabber 
> (YUV Sequence)
> 
> Generated YUV (I420 file size): 135 475 200.
> 1176 Frames grabbed (OK)
> 
> 
> 3) 3IVX MPEG-4 Splitter -> XVID Video Decoder -> Monograph FRAME Grabber 
> (YUV Sequence)
> 
> Generated YUV (I420 file size): 108 199 936.
> 939 Frames grabbed (NOK!)
> 
> 4) MPC MPEG-4 Splitter -> XVID Video Decoder -> Monograph FRAME Grabber 
> (YUV Sequence)
> 
> Generated YUV (I420 file size): 140 083 200.
> 1216 Frames grabbed (NOK!)
> 
> 
> 5) MPC MPEG-4 Splitter -> DivX Video Decoder -> Monograph FRAME Grabber 
> (YUV Sequence)
> 
> Generated YUV (I420 file size): 135 475 200.
> 1176 Frames grabbed (OK)
> 
> 
> Hope this helps you out a bit, if not, I can send you my complte batch 
> files, tools as well as the video sequence tested.
> 
> Best regards,
> Carl
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