[FFmpeg-trac] #7719(undetermined:closed): Extracting transparent PNGs from vp9a fails (vp8a works)
FFmpeg
trac at avcodec.org
Thu Feb 7 20:19:51 EET 2019
#7719: Extracting transparent PNGs from vp9a fails (vp8a works)
-------------------------------------+-------------------------------------
Reporter: rroller | Owner:
Type: defect | Status: closed
Priority: normal | Component:
| undetermined
Version: unspecified | Resolution: invalid
Keywords: vp9 alpha | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
Description changed by cehoyos:
Old description:
> {{{
> % ffmpeg -vcodec libvpx -i vp9a.webm -pix_fmt rgba out/image_%d.png
> }}}
> The codec's name is `libvpx-vp9`.
New description:
Extracting transparent PNG files from a vp8a webm video with an alpha
channel works. Extracting PNG files from a vp9a webm video with an alpha
channel does not work.
How to reproduce:
With a vp8a, no issue...
{{{
% ffmpeg -vcodec libvpx -i vp8a.webm -pix_fmt rgba out/image_%d.png
> produces transparent PNGs
}}}
Fails with a vp9a webm video:
{{{
% ffmpeg -vcodec libvpx -i vp9a.webm -pix_fmt rgba out/image_%d.png
fmpeg version 4.1 Copyright (c) 2000-2018 the FFmpeg developers
built with gcc 4.9.2 (Debian 4.9.2-10+deb8u2)
configuration: --enable-gpl --enable-libx264 --enable-libx265 --enable-
libwebp --enable-librsvg --enable-libvorbis --enable-libvpx --disable-
network
libavutil 56. 22.100 / 56. 22.100
libavcodec 58. 35.100 / 58. 35.100
libavformat 58. 20.100 / 58. 20.100
libavdevice 58. 5.100 / 58. 5.100
libavfilter 7. 40.101 / 7. 40.101
libswscale 5. 3.100 / 5. 3.100
libswresample 3. 3.100 / 3. 3.100
libpostproc 55. 3.100 / 55. 3.100
[libvpx @ 0x2d0c580] v1.8.0
[libvpx @ 0x2d0c580] Invalid sync code 430042.
[libvpx @ 0x2d0c580] Failed to decode frame: Bitstream not supported by
this decoder
[libvpx @ 0x2d0c580] Invalid sync code 844e49.
[libvpx @ 0x2d0c580] Failed to decode frame: Bitstream not supported by
this decoder
}}}
Versions:
{{{
ffmpeg version: 4.1 installed from source built on Debian 4.9.2-10+deb8u2
Also tried with ffmpeg from homebrew on a mac.
}}}
Here's ffprobe output for both vids:
{{{
ffprobe vp8a.webm
ffprobe version 4.1 Copyright (c) 2007-2018 the FFmpeg developers
built with gcc 4.9.2 (Debian 4.9.2-10+deb8u2)
configuration: --enable-gpl --enable-libx264 --enable-libx265 --enable-
libwebp --enable-librsvg --enable-libvorbis --enable-libvpx --disable-
network
libavutil 56. 22.100 / 56. 22.100
libavcodec 58. 35.100 / 58. 35.100
libavformat 58. 20.100 / 58. 20.100
libavdevice 58. 5.100 / 58. 5.100
libavfilter 7. 40.101 / 7. 40.101
libswscale 5. 3.100 / 5. 3.100
libswresample 3. 3.100 / 3. 3.100
libpostproc 55. 3.100 / 55. 3.100
Input #0, matroska,webm, from 'vp8a.webm':
Metadata:
encoder : libwebm-0.2.1.0
creation_time : 2019-02-07T21:34:38.000000Z
Duration: 00:00:11.00, start: 0.000000, bitrate: 392 kb/s
Stream #0:0(eng): Video: vp8, yuv420p(progressive), 1080x1920, SAR 1:1
DAR 9:16, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
Metadata:
alpha_mode : 1
ffprobe vp9a.webm
ffprobe version 4.1 Copyright (c) 2007-2018 the FFmpeg developers
built with gcc 4.9.2 (Debian 4.9.2-10+deb8u2)
configuration: --enable-gpl --enable-libx264 --enable-libx265 --enable-
libwebp --enable-librsvg --enable-libvorbis --enable-libvpx --disable-
network
libavutil 56. 22.100 / 56. 22.100
libavcodec 58. 35.100 / 58. 35.100
libavformat 58. 20.100 / 58. 20.100
libavdevice 58. 5.100 / 58. 5.100
libavfilter 7. 40.101 / 7. 40.101
libswscale 5. 3.100 / 5. 3.100
libswresample 3. 3.100 / 3. 3.100
libpostproc 55. 3.100 / 55. 3.100
Input #0, matroska,webm, from 'vp9a.webm':
Metadata:
encoder : libwebm-0.2.1.0
creation_time : 2019-02-07T15:31:54.000000Z
Duration: 00:00:11.00, start: 0.000000, bitrate: 281 kb/s
Stream #0:0(eng): Video: vp9 (Profile 0), yuv420p(tv), 1080x1920, SAR
1:1 DAR 9:16, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
Metadata:
alpha_mode : 1
}}}
--
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Ticket URL: <https://trac.ffmpeg.org/ticket/7719#comment:6>
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