[usf-devel] Re: [Matroska-devel] Request for a hi-speed bitmap compression formatstandard
- From: Christian HJ Wiesner <chris@xxxxxxxxxxxx>
- To: chris@xxxxxxxxxxxx,Discussion about the current and future development of Matroska <matroska-devel@xxxxxxxxxxxxxxxxxx>
- Date: Mon, 11 Aug 2003 14:10:58 +0200
Christian HJ Wiesner wrote:
> PNG was our first bet ( of course ), but unfortunately the results
> were proving that its unusable for our purpose, at least in its
> current form, as the necessary CPU power to decode a PNG compressed
> subtitle bitmap is simply too high. Imaging that we will play the
> movies on normal PCs ( min standard should be a PIII 800 MHz as per
> our recommendation ), and the CPU has to
>
> - decode the video, mainly MPEG4 or RealVideo9 ( very CPU intensive,
> especially for higher resolutions )
> - decode the audio, very often 5.1 AC3 or 5.1 AAC tracks
> - decode the compressed subtitle bitmap
Something weird came to my mind, and for very good reason i won't copy
the PNG and MNG lists on this email :
What do you think, how big would a MPEG1 compressed picture subtitle be
? MPEG1 has P/B frames already, so for a typical 720 x 574 ( numbers by
Gabest ) *DECODED* RLE VOBSUB bitmap with 4 bits per pixel ( 16 colours
in the main palette, 4 colours selected for every subpicture, equals 2
bits per pixel, but when decoded the bitmap can be shown as 4 bits per
pixel in full resolution ). MPEG normally performs pretty well on
single coloured ( black ) backgrounds already, and we could maybe bring
the overhead down significantly by using lacing ?
MPEG1 encoding is free, and MPEG1 decoding is fast
Crazy idea ?
Christian
http://usf.corecodec.org
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