Opened 10 years ago

Closed 10 years ago

Last modified 10 years ago

#1106 closed enhancement (worksforme)

10 bit RGB DPX file identified as rgb48le

Reported by: dave rice Owned by:
Priority: wish Component: avcodec
Version: git-master Keywords: dpx gbr10
Cc: Blocked By:
Blocking: Reproduced by developer: yes
Analyzed by developer: no

Description

These DPX image files as 10 bit RGB; however ffmpeg identifies them as rgb48le rather than gbrp10le.

Sample here: http://www.archive.org/download/Sample10BitRgbDpxFile/00255.dpx

ffmpeg -i 00255.dpx
ffmpeg version N-35294-g2d38081 Copyright (c) 2000-2012 the FFmpeg developers
  built on Mar 12 2012 21:13:33 with gcc 4.2.1 (Apple Inc. build 5666) (dot 3)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD --enable-shared --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-libfreetype --cc=/usr/bin/gcc-4.2 --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libxvid --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libass
  libavutil      51. 42.100 / 51. 42.100
  libavcodec     54. 10.100 / 54. 10.100
  libavformat    54.  2.100 / 54.  2.100
  libavdevice    53.  4.100 / 53.  4.100
  libavfilter     2. 64.101 /  2. 64.101
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0.  7.100 /  0.  7.100
  libpostproc    52.  0.100 / 52.  0.100
Input #0, image2, from '00255.dpx':
  Duration: 00:00:00.04, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: dpx, rgb48le, 2048x1556 [SAR -1:-1 DAR 512:389], 25 tbr, 25 tbn, 25 tbc
At least one output file must be specified

Change History (4)

comment:1 by Carl Eugen Hoyos, 10 years ago

Component: undeterminedavcodec
Keywords: dpx gbr10 added
Priority: normalwish
Reproduced by developer: set
Status: newopen
Type: defectenhancement

The dpx file is packed RGB and has 10 bits per component and is correctly identified (and transcoded).
At the time the decoder was written, the only colourspace that could save information was RGB48.
This could now be changed to planar GBR10, but I don't think it makes much sense to convert from packed to planar, so I will close this ticket.

Last edited 10 years ago by Carl Eugen Hoyos (previous) (diff)

comment:2 by Carl Eugen Hoyos, 10 years ago

Resolution: worksforme
Status: openclosed

comment:3 by dave rice, 10 years ago

When I convert the DPX to raw rgb48le then there is random data in bits 11-16 for each channel. Is the conversion of this DPX to raw rgb48le not a lossless conversion? Where does this extra data come from?
...
OK, looking closer it seems that bits 11-16 are a copy of bits 1-6, so the 10 bit DPX sample decodes to bit:1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6. Is there a way to prevent this, as it seems to just add noise in the lesser significant bits?

in reply to:  3 comment:4 by Michael Niedermayer, 10 years ago

Replying to dericed:

When I convert the DPX to raw rgb48le then there is random data in bits 11-16 for each channel. Is the conversion of this DPX to raw rgb48le not a lossless conversion? Where does this extra data come from?
...
OK, looking closer it seems that bits 11-16 are a copy of bits 1-6, so the 10 bit DPX sample decodes to bit:1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6. Is there a way to prevent this, as it seems to just add noise in the lesser significant bits?

The bits replication is needed to maintain pure white and pure black. Consider 1bit mono to be converted to lets say 8 bit without replication it would become gray/black.

Note: See TracTickets for help on using tickets.