[linux-dvb] Re: mplex and mpegtools 2gb limit

[Marcus Metzler <mocm@metzlerbros.de>]

'Chris Pitchford' writes:
 > 
 > Hi again,
 > 
 > I tried the package in the URL posted to the list a few hours ago and have
 > definately got further.... but.....
 > 
 > I tried using dvb-mplex to convert a TS_STREAM into a "mpg" file, as I
 > have done previously (though only with files <2GB).
 > 
 > Again, it hangs after completing the demuxing of the TS_Stream into
 > tmp_as.mp2 and tmp_vs.m2v.
 > 
 > I used the new version of ts2es to split the TS_STREAM into two files aud
 > and vid as I tried before.....
 > 
 > # ts2es DVB-9-20021127-2059.36+2h10m.ts 1 > vid
 > # ts2es DVB-9-20021127-2059.36+2h10m.ts 2 > aud
 > 
 > Both times when it reaches the end of the TS file, and looks like it has
 > completed vid and aud, it hangs.. in exactly the same way dvb-mplex hangs
 > with:
 > # dvb-mplex -t MPEG2 -o test.mpg -i TS_STREAM DVB-9-20021127-2059.36+2h10m.ts


I'll have to check that. 

 > 
 > VPTS - APTS = 0ms

During demux this difference is calculated, so that you have to set it
by hand if you start with demuxed files.

 > 
 >   Scanning video stream for a sequence header and pulldown type ...
 >     no pulldown detected ...
 > 
 >   Scanning video stream for pictures ...
 >   Found 187520 picture headers, stream bit offset 36267495408.8751.
 >   Video stream information
 >     Stream length : 238469630
 >     Total time (seconds) : 7500
 >     Sequence start : 15628
 >     Sequence end : 0
 >     No. Pictures : 187520
 >     No. Groups : 15628
 >     No. I Frames : 15628 avg. size 68370 bytes
 >     No. P Frames : 46880 avg. size 33197 bytes
 >     No. B Frames : 125012 avg. size 15267 bytes
 >     No. D Frames : 0 avg. size 0 bytes
 >     Horizontal size : 720
 >     Vertical size : 576
 >     Aspect ratio : 0.7031
 >     Picture rate : 25.000 frames/sec
 >     Bit rate : 556250 bytes/sec (4450000 bits/sec)
 >     Computed avg rate : 32500 bytes/sec (260000 bits/sec)
 >     Computed max rate : 929550 bytes/sec (7436400 bits/sec)
 >     Vbv buffer size : 229376 bytes
 >     CSPF : 0
 > 
 >   Scanning audio stream for access units information
 >   Found 312541 audio frame headers, stream bit offset 1920284160.
 >   MPEG audio stream information
 >     Stream length : 240035520
 >     Syncwords : 312541
 >     Frames : 312541 size 768 bytes
 >     Frames : 0 size 769 bytes
 >     Layer : 2
 >     CRC checksums : yes
 >     Bit rate : 32000 bytes/sec (256 kbit/sec)
 >     Frequency : 48.0 kHz
 >     Mode : 0 stereo
 >     Mode extension : 0
 >     Copyright bit : 0 no copyright
 >     Original/Copy : 0 copy
 >     Emphasis : 0 none
 > 
 >   Multiplexing information
 >     Video stream data rate : 929550 bytes/sec (7436400 bits/sec)
 >     Audio stream 1 data rate : 32000 bytes/sec (256000 bits/sec)
 >     Overhead data rate : 17250 bytes/sec (138000 bits/sec)
 >     Total data rate : 978800 bytes/sec (7830400 bits/sec)
 > 
 >   Multiplexing file test.mpg
 >   Finished multiplexing test.mpg
 > </snip>
 > 
 > 
 > Problems: The percentage when scanning the video stream for pictures:
 > 
 > Scanning video stream: 1301% - byte offset 3103261188 of 238528751.
 > 
 > erm?! the percentage goes up to over 2000%, perhaps the "max value" is
 > only the least significant 32 bits of the file size, since here its
 > 238Million?? :-o Anyway, Thats cosmetic

Probably some overflow for a variable that should be int64_t instead
of something smaller. I have to search for that. First I need to
record a file >2GB.

 > 
 > When the stream eventually finished, the audio was out of sync by over a
 > second.. Something I've not seen before. I don't know if this was a result
 > of using ts2es FIRST, then using dvb-mplex to join to ES_STREAMS (again
 > soemthing Ive never needed to do before) or if its something to do with
 > the software and/or my system???
 > 

See above. There is no time stamp in the ES files, so the offset
between audio and video has to be determined by hand.

Check our website for an update. I'll see if I can get to fixing the problem
this weekend.

Marcus

-- 
/--------------------------------------------------------------------\
| Dr. Marcus O.C. Metzler        |                                   |
|--------------------------------|-----------------------------------|
| mocm@metzlerbros.de            | http://www.metzlerbros.de/        |
\--------------------------------------------------------------------/




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