em28xx_isoc_dvb_max_packetsize for EM2884 (Terratec Cinergy HTC Stick)

Dennis Sperlich
2011-12-24T21:58:15Z

Hi,

I have a Terratec Cinergy HTC Stick an tried the new support for the
DVB-C part. It works for SD material (at least for free receivable
stations, I tried afair only QAM64), but did not for HD stations
(QAM256). I have only access to unencrypted ARD HD, ZDF HD and arte HD
(via KabelDeutschland). The HD material was just digital artefacts, as
far as mplayer could decode it. When I did a dumpstream and looked at
the resulting file size I got something about 1MB/s which seems a little
too low, because SD was already about 870kB/s. After looking around I
found a solution in increasing the isoc_dvb_max_packetsize from 752 to
940 (multiple of 188). Then an HD stream was about 1.4MB/s and looked
good. I'm not sure, whether this is the correct fix, but it works for me.

If you need more testing pleas tell.

Regards,
Dennis

index 804a4ab..c518d13 100644
--- a/drivers/media/video/em28xx/em28xx-core.c
+++ b/drivers/media/video/em28xx/em28xx-core.c
@@ -1157,7 +1157,7 @@ int em28xx_isoc_dvb_max_packetsize(struct em28xx *dev)
* FIXME: same as em2874. 564 was enough for 22 Mbit DVB-T
* but not enough for 44 Mbit DVB-C.
*/
- packet_size = 752;
+ packet_size = 940;
}

return packet_size;