[ATrpms-users] dvdauthor error
Jeffrey J. Kosowsky
atrpms at kosowsky.org
Wed Jan 16 04:45:26 CET 2008
Axel Thimm wrote at about 22:26:41 +0200 on Tuesday, January 15, 2008:
> On Tue, Jan 15, 2008 at 01:01:51PM -0500, Jeffrey J. Kosowsky wrote:
> > Axel Thimm wrote at about 18:43:30 +0200 on Tuesday, January 15, 2008:
> > > On Thu, Jan 10, 2008 at 09:01:50AM -0500, Jeffrey J. Kosowsky wrote:
> > > > Now, according to the log file (see above), the xml file seemed to
> > > > specify a bitrate of "15000000" (or 15mb/sec),
> I looked this up and 15 MB/sec is the mpeg2 default for
> 720x576 at 30Hz. So maybe this is what the xml file maps to?
> OTOH DVD bitrates define a max peak at about 10MB/sec (e.g. in this
> sense DVD is not really a full mpeg2 implementation), while DVB allows
> the full 720x576 at 30Hz bitrate.
> E.g. I think you will always need to transcode a full (SDTV) DVB
> stream to allow recording on DVD.
> > > > which would exceed the 1080kb/sec limit. On the other hand
> > > > since the actual recording was 2 hours long and the total
> > > > length was 2.85GB, the (average) bitrate was more like
> > > > 3.1kb/sec (2850000*8/3600/2). So, unless the bitrate is highly
> > > > variable (this is an atsc dvb recording), it probably did not
> > > > exceed the limit too much.
> > >
> > > I think you missed a couple of zeros in the GB :)
> > >
> > > E.g. it's more like 2.85 * 1024^3 Bytes (kilo -> mega -> giga).
> > >
> > > > So, I'm not really sure what is going on here unless it really is a
> > > > bitrate issue with the variable bitrate truly exceeding the dvd max
> > > > too often.
> > > >
> > > > Any thoughts/advice here...
> > >
> > > Does the missing "1000" fix this? At least is seems to bring the
> > > numbers in the same order.
> > > --
> > You are right - I did the conversion to kilobytes twice :)
> > i.e. the answer is: 2850000*8/3600/2 kb/sec = 3166 kb/sec = 3.2mb/sec
> > However, 3.2 mb/sec = 0.4 mB/sec which should not be exceeding the
> > dvd rate -- an easy way to see this is that a full 2 hours of
> > recording fit in 2.85GB of space and we all know that a regular 2 hour
> > mpeg2 commercial DVD movie takes up more than that...
> 3 Mbit/sec sounds more like 352 × 288/240 resolution. Was that the
> resolution of the captured file? In that case the DVB and DVD
> standards of mpeg2 overlap, but then you need to make TS to PS, so I
> think at the end you will always have to transcode DVB->DVD formats.
I'm not sure what the original resolution was and I have since
transcoded it. But, I just looked at another recording that according
to mplayer is:
VIDEO: MPEG2 704x480 (aspect 2) 29.970 fps 15000.0 kbps (1875.0 kbyte/s)
However, the 1/2 hour recording is exactly 995413188 bytes, which
corresponds to: 995413188/1800 = 553007 bytes/s = 553 kbyte/s = 4424
This again seems close to the "Low Level - 352x288" flavor of mpeg-2
but I am confused to why mplayer calls it 702x480 and 15000 kbps...
> > So, while my math was sloppy :), the problem remains unsolved for me
> > again unless there is huge variability in the bitrate which results in
> > transitory speeds much higher than 0.4 megabyte/sec. (or so it seems
> > to me :)
> Maybe it isn't a bitrate but a format problem then?
> Axel.Thimm at ATrpms.net
> [GNUPG:] ERRSIG 401552D4639A99F1 17 2 01 1200428801 9
> [GNUPG:] NO_PUBKEY 401552D4639A99F1
More information about the atrpms-users