[FFmpeg-trac] #3137(undetermined:closed): bitrate artifacts with libvpx (was: bitrate artefacts with libvpx)

[FFmpeg]

#3137: bitrate artifacts with libvpx
-------------------------------------+-------------------------------------
             Reporter:  ubitux       |                    Owner:
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:
              Version:  unspecified  |  undetermined
             Keywords:  libvpx       |               Resolution:  invalid
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
-------------------------------------+-------------------------------------
Changes (by ubitux):

 * status:  new => closed
 * resolution:   => invalid


Old description:

> When encoding a webm/vp8 with default settings, some weird artefacts
> appear at regular intervals.
>
> {{{
> ☭ ./ffmpeg -loop 1 -i tests/lena.pnm -vf 'scale=2*iw:2*ih' -t 20 -y
> out.webm
> ffmpeg version N-58093-g54af7ce Copyright (c) 2000-2013 the FFmpeg
> developers
>   built on Nov 14 2013 19:11:51 with gcc 4.8.2 (GCC)
>   configuration: --enable-gpl --enable-libx264 --enable-libmp3lame
> --enable-x11grab --enable-libvorbis --samples=/home/ux/fate-samples
> --enable-libfreetype --enable-libvpx --cpu=native --cc='ccache cc'
>   libavutil      52. 53.100 / 52. 53.100
>   libavcodec     55. 43.100 / 55. 43.100
>   libavformat    55. 21.100 / 55. 21.100
>   libavdevice    55.  5.100 / 55.  5.100
>   libavfilter     3. 91.100 /  3. 91.100
>   libswscale      2.  5.101 /  2.  5.101
>   libswresample   0. 17.104 /  0. 17.104
>   libpostproc    52.  3.100 / 52.  3.100
> Input #0, image2, from 'tests/lena.pnm':
>   Duration: 00:00:00.04, start: 0.000000, bitrate: N/A
>     Stream #0:0: Video: ppm, rgb24, 256x256, 25 fps, 25 tbr, 25 tbn, 25
> tbc
> [libvpx @ 0x181a160] v1.2.0
> Output #0, webm, to 'out.webm':
>   Metadata:
>     encoder         : Lavf55.21.100
>     Stream #0:0: Video: vp8 (libvpx), yuv420p, 512x512, q=-1--1, 200
> kb/s, 1k tbn, 25 tbc
> Stream mapping:
>   Stream #0:0 -> #0:0 (ppm -> libvpx)
> Press [q] to stop, [?] for help
> frame=  500 fps=149 q=0.0 Lsize=     434kB time=00:00:20.00 bitrate=
> 177.9kbits/s
> video:431kB audio:0kB subtitle:0 global headers:0kB muxing overhead
> 0.898042%
> }}}
>
> Then play {{{out.webm}}}: at t=5s, t=10s and t=15s, one single frame gets
> "flashy" (just like if bitrate was wrong/very-low for those frames). It's
> less visible if bitrate is raised but still visible (try adding {{{-b:v
> 1M}}}).
>
> It's probably some kind of rate control bug in libvpx, but maybe
> something is wrong in the wrapper (I don't have time to dig this issue)
> so I'm opening a ticket.

New description:

 When encoding a webm/vp8 with default settings, some weird artifacts
 appear at regular intervals.

 {{{
 ☭ ./ffmpeg -loop 1 -i tests/lena.pnm -vf 'scale=2*iw:2*ih' -t 20 -y
 out.webm
 ffmpeg version N-58093-g54af7ce Copyright (c) 2000-2013 the FFmpeg
 developers
   built on Nov 14 2013 19:11:51 with gcc 4.8.2 (GCC)
   configuration: --enable-gpl --enable-libx264 --enable-libmp3lame
 --enable-x11grab --enable-libvorbis --samples=/home/ux/fate-samples
 --enable-libfreetype --enable-libvpx --cpu=native --cc='ccache cc'
   libavutil      52. 53.100 / 52. 53.100
   libavcodec     55. 43.100 / 55. 43.100
   libavformat    55. 21.100 / 55. 21.100
   libavdevice    55.  5.100 / 55.  5.100
   libavfilter     3. 91.100 /  3. 91.100
   libswscale      2.  5.101 /  2.  5.101
   libswresample   0. 17.104 /  0. 17.104
   libpostproc    52.  3.100 / 52.  3.100
 Input #0, image2, from 'tests/lena.pnm':
   Duration: 00:00:00.04, start: 0.000000, bitrate: N/A
     Stream #0:0: Video: ppm, rgb24, 256x256, 25 fps, 25 tbr, 25 tbn, 25
 tbc
 [libvpx @ 0x181a160] v1.2.0
 Output #0, webm, to 'out.webm':
   Metadata:
     encoder         : Lavf55.21.100
     Stream #0:0: Video: vp8 (libvpx), yuv420p, 512x512, q=-1--1, 200 kb/s,
 1k tbn, 25 tbc
 Stream mapping:
   Stream #0:0 -> #0:0 (ppm -> libvpx)
 Press [q] to stop, [?] for help
 frame=  500 fps=149 q=0.0 Lsize=     434kB time=00:00:20.00 bitrate=
 177.9kbits/s
 video:431kB audio:0kB subtitle:0 global headers:0kB muxing overhead
 0.898042%
 }}}

 Then play {{{out.webm}}}: at t=5s, t=10s and t=15s, one single frame gets
 "flashy" (just like if bitrate was wrong/very-low for those frames). It's
 less visible if bitrate is raised but still visible (try adding {{{-b:v
 1M}}}).

 It's probably some kind of rate control bug in libvpx, but maybe something
 is wrong in the wrapper (I don't have time to dig this issue) so I'm
 opening a ticket.

--

Comment:

 The issue is reproducible with libvpx, I'm closing the issue as it can't
 be fixed in FFmpeg. See http://code.google.com/p/webm/issues/detail?id=717
 for details.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/3137#comment:1>
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