Log in

View Full Version : what's crc?


zoli
5th July 2002, 13:47
i ripped a dvd and demuxed the ac3 streams with dvd2avi. i couldn't rip the vobs straight away from the dvd rom, as towards the last vobs, the disc speed fell to a modest 0.1x or the sort. so i copied all to the hd and descrambled it from there.
after transcoding the ac3 to 128k mp3 using besweet, the conversion is done but the log file says i have 4-5 crcs in the mp3.

i tried besplit on the ac3 stream, same result.

when i listen to the timepoints in the mp3 stream where besweet suggested crcs, i hear no skip, no artifact, nothing out of order.
i searched the forum for crc related stuff, but all i gathered was that people having crc streams observed skipping, artifacts, i don't know what else. that i obviously don't have.

my question is, should i be concerned because of these crcs? if i hear nothing unexpected, then should i put up with the crc stream and keep my mouth shut? or what do the pros think of this?

DSPguru
5th July 2002, 14:31
crc is an alogrithm for error detection.
whenever BeSweet finds a crc error (error in ac3 bitstream) it switches the corrupted frame samples with 32miliseconds of silence.
therefore, a few crc errors are indistinguished.


btw,
may i see your BeSplit logfile ?

zoli
5th July 2002, 15:59
thanks for the reply.
sure, here comes the besplit log:

BeSplit v0.7 logfile.
--------------------------
Logging start : 07/04/02 , 23:19:13.

C:\Program Files\OGG\BeSplit\BeSplit.exe -core( -logfile D:\hifi cut AC3 T01 3_2ch 384Kbps DELAY -80ms.LOG -input E:\VIDEO_TS\hifi cut AC3 T01 3_2ch 384Kbps DELAY -80ms.ac3 -prefix D:\hifi cut AC3 T01 3_2ch 384Kbps DELAY -80msFIX -type ac3 -a -fix )

[00:00:00:000] +------- BeSplit -----
[00:00:00:000] | Input : E:\VIDEO_TS\hifi cut AC3 T01 3_2ch 384Kbps DELAY -80ms.ac3
[00:00:00:000] | Output Prefix : D:\hifi cut AC3 T01 3_2ch 384Kbps DELAY -80msFIX
[00:00:00:000] +---------------------
[01:49:13:216] | Writing D:\hifi cut AC3 T01 3_2ch 384Kbps DELAY -80msFIX01.ac3
[01:49:13:216] +---------------------
[01:49:13:216] Operation Completed !
[00:02:26:000] <-- Process Duration
Logging ends : 07/04/02 , 23:21:39.