[FFmpeg-trac] #3137(undetermined:closed): bitrate artifacts with libvpx (was: bitrate artefacts with libvpx)
FFmpeg
trac at avcodec.org
Thu Feb 27 11:57:21 CET 2014
#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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