On 06/12/2014 09:31 AM, rogerx....@gmail.com wrote: > I have a script which uses 'dd' (instead of 'cat') for capturing a timed DVB > stream or feed for 30, 60, 90, ... minutes. (From memory, I stopped using > 'cat' a long time ago either because 'cat' had problems with TV channels > containing static or due to large file size.) > > A sporadic error received when using 'dd' is the following: > > --- Snip --- > /mnt/archives1/tv/20140611-1700-ch9.1-60min.mpg > > dd: error reading '/dev/dvb/adapter0/dvr0': Value too large for defined data > type > 73145+0 records in > > 73145+0 records out > > 37450240 bytes (37 MB) copied, 38.2406 s, 979 kB/s > > dd: warning: invalid file offset after failed read > --- Snip --- > > My guess is, since dd doesn't know the exact initial size or the proper > number > of interval bytes, dd spawns this error. Or, there maybe static within the > signal or overload. Although my rational doesn't seem to match the given > error, sometimes errors might be just generic in a sense. (ie. 'dd' was > likely > engineered for file copying, and copying a live stream was later.) > > My second guess, there's likely no way to avert the error and is likely a > harmless error. > > Channel 9.1 is PBS at my location over DVB TV, a large file at times: > VIDEO: MPEG2 1280x720 (aspect 3) 59.940 fps 24000.0 kbps (3000.0 kbyte/s) > AUDIO: 48000 Hz, 2 ch, ac3be, 384.0 kbit/25.00% (ratio: 48000->192000) > > Bottom line, the recorded video file (stream) looks just fine and I don't > think > I've ever seen any anomalies. If any video/audio problems created by this > error, I've never see a player or editor complain, or the editor > automatically > fixes the file. >
It seems dd is only reporting the EOVERFLOW from the read() syscall. That error seems specific to the kernel DVB drivers: https://tvheadend.org/boards/5/topics/8378?r=8414 cheers, Pádraig.
