On Tue, Nov 20, 2001 at 08:54:45AM +0200, Justin Schoeman wrote: > > The sort of jerkiness you are talking about is typically the result of 1 > of 2 things: > > 1) Hard disk speed is too slow. To fix this, use hdparm to optimise your > drive settings, or use a compression algorithm with higher compression > ratios. Well, if I were using an mpeg/divx/div4 bitrate of (say) 1800kbps that is only 230,400 bytes/s required disk throughput. Even over NFS I can achieve 6.7 megabytes/s: $ time dd if=/dev/zero of=/video/test.avi bs=1024k count=100 100+0 records in 100+0 records out 0.00user 0.85system 0:14.82elapsed 5%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (144major+25minor)pagefaults 0swaps [brian@pc NVrec-20011102]$ ls -l /video/test.avi -rw-rw-r-- 1 brian brian 104857600 Nov 20 03:09 /video/test.avi So disk can hardly be the issue right? Or is there something other than raw throughput that I am missing? > 2) Your CPU is too slow to compress the video real-time. In this case, > use a faster compression algorithm. Well like I said I have tried just about all of them out there and mp1e seems to give the best results. It is also the one that pushes the pin on the CPU-o-meter the least. > (Possible 3: If you only get this when recording from a VCR, try the > VCR hack that was posted to the list a while ago - this helps a lot if > your VCRs playback timing is slightly off.) Definately not this issue. I am recording direct off of cable (analog). > You may notice that these two are contradictory - so you need a fast HDD > or a fast CPU, or preferably, both. I think I have both. My CPU is an AMD Athlon-800 (Thunderbird). > I have an Athlon 600, and use DIVX4rec with the "-dq3" option. I tried that just now. I am floored by the quality -- compared to what I have been getting in the past. I like! I like! I am sure I tried all of the XXXrec tools in the past and none were working all that well. Hmmmm. You know now that I think of it, I think the problem I had with the DIVX*rec tools was that the playback seemed to "smear" with Mplayer. Any ideas on that? It seems alright now but if it were to happen again it would help to know what to look for. > It never > drops any frames, I only got frame drops when I asked the computer to do something else simultaneously. :-) > and the quality is still pretty good. Indeed. > On a PIII-800, > I use "-dq 5", and the quality is awesome...) I compared -dq 3 and -dq5 recording from analog cable and I don't think I see much of a difference. I think to be sure I would need to encode the same clip from cable twice so I could actually compare side by side. Who cares though? -dq3 looks good. :-) > mp1e is the best low-cpu option I > have ever seen, Indeed! > but I have had many problems with A/V synch. Me too! I guess we can just hope and wait for RTE to work with RTErec. Something I did notice in going back over the XXXrec tools: DIVX4rec seems to have an A/V lag. The audio and video seem to be out somewhere between a half a second to a second. Using DIVXrec seems to be just fine however. b. -- Brian J. Murrell
