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View Full Version : Large FLV chokes when seeking on CD


rondog
11-16-2009, 05:10 PM
I have a FLV about 5.5 minutes long at 2000kbps. Its 85mb. 704x400.

When I start playing the FLV on the CD and I seek to the end, it has a very hard time seeking to the end. It takes quite a long time to finally catch up. When I play the projector on my hard drive it plays just fine.

Any idea why? I am using the standard FLV component

northcode
11-16-2009, 05:27 PM
It sounds a latency issue, the FLV has to be scanned and the CD drive doesn't seek as fast as your HD can. Start copying everything on your C: drive to your D: drive and then retry your FLV test on your HD. The FLV test should suck in that case too. The apparent "bigness" is directly affected by the transfer speed. It would probably take you several lifetimes to write out the bytes from that file by hand ;)

rondog
11-16-2009, 05:48 PM
Thats weird its not even that big of a file..85mb doesnt seem that big anyway.

rondog
11-16-2009, 05:56 PM
I also noticed that if I let it play through all the way and then try seeking, it seeks fine. Its just when its viewed for the first time

northcode
11-16-2009, 08:45 PM
It's probably cached by then. If not by Flash then by the OS. Divide the size of your video by the CD drive's maximum transfer rate to get the theoretical maximum time it would take just to load the file without decompresing it or parsing the FLV data and you'll get some idea of why it's so much slower to access things from CD.

rondog
03-10-2010, 07:57 PM
I've still found no solution for this...anyone have some ideas?

northcode
03-10-2010, 08:27 PM
The only real option is to copy the FLV to the HD as part of a setup process and play it from the much faster HD.

CyanBlue
03-10-2010, 09:00 PM
As northcode mentioned already, that's the latency issue where it takes longer time to load something from the CD-Rom drive... Either move the video file to HDD or prepare multiple FLV files out of big FLV file to reduce the seek time...

rondog
07-13-2010, 11:37 PM
You know I never really thought it was a latency issue because playing a WMV file burned on a CD file never had the problem. Today I've found the perfect solution. I took the same 1 hour and 50 minute movie and encoded one as an FLV (480x360 @ 750kbps) and the other as an h.264 mp4 (same window size and data rate)

I burned them to a disc and the FLV choked up like normal and basically froze while trying to seek the long file.

When I seeked the MP4, it seeked just fine. Its the FLV codec that is the issue here.

So ladies and gents...the solution is use the h.264 codec if you plan on putting seekable video onto a disc.

northcode
07-14-2010, 03:30 AM
That might not be the whole answer. I know the FLV codec in Flash 10 caches the entire FLV to the HD to play it and not just FLV files that play from the web. It doesn't store them in the browser cache though, it creates a temp file somewhere else. I know this because we were trying to create a secure system for FLV playback and the Flash player made that incredibly difficult by caching every FLV for us whether we wanted it to or not.

rondog
07-14-2010, 05:27 AM
I dont understand your argument. It's pretty simple.

The same source, encoded as an FLV and as an H.264 MP4 playing back in the same player off of a disc.

The FLV chokes and the MP4 seeks flawlessly.

northcode
07-14-2010, 07:03 PM
The codec Flash uses to play the mp4 file might be doing more caching than the FLV codec. I think the FLV codec created a new temp file for every play. The MP4 might be smarter and only creating one copy of the mp4 file. If you play it once, it might not touch the CD again if it sees the file is already cached. OR you could be right and mp4 could just be more efficient than the plain FLV codec. However, it "canna break the laws of physics" by pulling data from the CD faster than it's theoretical maximum transfer rate. If you see that happen, it's cached on the HD somewhere.

rondog
07-15-2010, 06:11 PM
I tried the disc on multiple machines so it cant be because the file had been cached.

northcode
07-15-2010, 07:15 PM
A 1X CD-ROM can transfer 150 KB/sec and a 72X CD-ROM can transfer about 10.5 MB/sec. So on a 72X drive, if your file is encoded at 2000 KB/sec (2 MB/sec) then you shouldn't have any problems unless the drive spins down and you have to wait for it to spin up again. On a 16X drive (2.3 MB/sec) you're flirting in the danger zone. Anything slower than a 16X drive won't be able to keep up with the demand no matter how good the codec is.

northcode
07-15-2010, 08:05 PM
Not disputing the fact that H.264 may work better than FLV but just saying watch out for the hardware factor. It will spin around and bite you when you least expect it :)