[libav-bugs] [Bug 519] New: Lossless qtrle video encoding from series of images not lossless

bugzilla-daemon at aruru.libav.org bugzilla-daemon at aruru.libav.org
Sun May 19 09:26:12 CEST 2013


           Summary: Lossless qtrle video encoding from series of images
                    not lossless
           Product: Libav
           Version: 0.8
          Platform: All
        OS/Version: Linux
            Status: NEW
          Severity: major
          Priority: Normal
         Component: general
        AssignedTo: bugzilla at libav.org
        ReportedBy: drx at a-blast.org

Created attachment 410
  --> https://bugzilla.libav.org/attachment.cgi?id=410
Original PNG (left) and first frame of video (right)

When converting a set of PNG of BMP images to a video with the qtrle codec, the
resulting video's frames are notably different from the source frames.

The frames should be reproduced pixel perfect in the video.

This command line was used to create a video from the PNG files:

avconv -f image2 -r 30 -i frames-flat.png/wth-%08d.png -vcodec qtrle -pix_fmt
rgb24 -t 15 flat-matte-qtrle-30fps-rgb.mov

avconv encoded the video without auto-inserting any filters:

avconv version 0.8.6-4:0.8.6-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the
Libav developers
  built on Apr  2 2013 17:02:36 with gcc 4.6.3
Input #0, image2, from 'frames-flat.png/wth-%08d.png':
  Duration: 00:06:18.80, start: 0.000000, bitrate: N/A
    Stream #0.0: Video: png, rgb24, 1280x800, 30 fps, 30 tbr, 30 tbn, 30 tbc
[buffer @ 0x1c7f520] w:1280 h:800 pixfmt:rgb24
Output #0, mov, to 'flat-matte-qtrle-30fps-rgb.mov':
    encoder         : Lavf53.21.1
    Stream #0.0: Video: qtrle, rgb24, 1280x800, q=2-31, 200 kb/s, 30 tbn, 30
Stream mapping:
  Stream #0:0 -> #0:0 (png -> qtrle)
Press ctrl-c to stop encoding
frame=  450 fps=  9 q=0.0 Lsize=  126056kB time=15.00 bitrate=68843.4kbits/s 

However, the resulting video looks like the frames have went through a
colorspace conversion, see the attachment.

If you are interested in more source material, please let me know.

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