[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
 }}}

--

--
Ticket URL: <https://trac.ffmpeg.org/ticket/7719#comment:6>
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