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Re: [VCDImager] Still Pictures and MPG music (really, just music)

From: Herbert Valerio Riedel
Subject: Re: [VCDImager] Still Pictures and MPG music (really, just music)
Date: Fri, 12 Jan 2001 12:34:03 +0100 (CET)


On Thu, 11 Jan 2001, Rick Stuart wrote:
> I haven't tried the software yet, but poking through the source
> code I found interesting evidence of different VCD formats which
> include still pictures and sound.
yes... it is possible to add still pictures to a vcd as segment items...
(and I guess it should be possible to have audio only streams too, but I'm
not sure on that one...)

anyway, GNU VCDImager does not support adding segment items to a
(S)VCD yet(!) ...

> Let me get to the point - is it possible to set up a VCD with
> hours of MPEG encoded/compressed sound/music and little video
> data?

I'm sure it is, but I don't know if players are able to play it back :^)

(actually for SVCD's it is definitely supported to have audio only segment
items... (though it is restricted to MPEG1 layer2 VBR ranging from 32 to
384 kbps...)
I guess it may be supported for VCD2.0 as well, but I'm not sure on
that one...)

> So far, from what I've read, it looks like the bit rate of the video
> has to be close to a nominal value.  If so are all VCDs limited to
> about an hour of material no matter what the content?
well, as for VCDs the bitrate _should_ be fixed at ~1.15mbps, but you can
use higher bitrates as well and you may lose the ability to play it on
some older VCD hardware (such as CD-i players and VCD players, which have
single speed cdrom drives)

...and for SVCDs you are allowed for bitrates up to 2.6mbps...

> Also, I can't find information anywhere about the difference between
> VCD11 and VCD2 formats.  It looks like VCD2 is a little bit VCD11 and
> a little bit SVCD from the VCDImager source code.  But before I burn
> too many CDs, I'd like to know what my DVD player can read.

as to the features (I've forgotten some stuff, and I may be wrong on some
minor details -- plz correct me if you notice anything)

vcd 1.1)
* up to 98 mpeg1(greenbook)/cdda (redbook) tracks
* only NTSC/FILM video resolution expected (it may work putting PAL on
  them, but afaik PAL compatibility was added with vcd 2.0)
* entry points support
* simple multi multivolume support
* CD-i support

vcd 2.0)
* features of vcd 1.1
* playback control aka PBC (loop, jumping, delaying, extended
  multivolume support, etc...)
* menu support (selection lists based on still images)
* segment items (still images)
* PAL officially supported
* restriction field support

svcd 1.0)
* features of vcd 2.0
* mpeg2 VBR instead of mpeg1 CBR (+ higher/other resolutions)
  thus leading to better image quality
  (imho you don't notice any big difference between a DVD and a
  (well made) SVCD on average television equipment...)
* no CDDA tracks
* no CD-i support
* overlay graphics
* multilingual
* subtitling

actually most DVD players should be able to read vcd 2.0 conforming
videocds, but some players work a bit better with vcd 1.1 disks...

a note from Nuno Dias I got on his experiments:
>Anyway, I can leave you this quick report summary to help Philips DVD
>players owner's making vcd's with vcdimager:
>  1- To have the fast forward and rewind feature enabled: The mpeg files
>should be made with "sequence header before EVERY GOP".
>  2- To have the time and track info on the player's display: The vcd
>image should be made with any software supporting VCD 1.1 (NOT 2.0) like 
>vcdimager --type=vcd11 ...
>  3- This player do not support SVCD's (it ejects the CD).

Herbert Valerio Riedel      /     Finger address@hidden for GnuPG Public Key
GnuPG Key Fingerprint: AC2A CD57 A5C8 A1CB 0A18  DA95 CB0B DB23 60B6 16F5

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