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Xesdeeni
17th August 2005, 16:53
I'm trying to capture some analog video using the FusionHDTV card on my HTPC. It's in a 2600+ machine, but when using HuffYUV (2.1.1), I get a large number of dropped frames.

Oddly, if I use the uncompressed RGB format, I get very few dropped frames. I usually get one or two right at the start. Then, after 10-20 minutes I can get 10s of dropped frames, which I assume is related to hard drive thermal recalibration. But I'm trying to capture a 30 minute show for conversion to DVD, so I don't want any dropped frames.

Does anyone know what could be causing HuffYUV to drop frames? I assume it's having trouble compressing the frames quickly enough, but the machine is pretty fast (real time HD playback, good speed on MPEG compression, 35+ MB/s transfer rates, etc.).

Is HuffYUV's compression efficient enough for real time capture? Are there better codec choices for this?

Xesdeeni

mic
17th August 2005, 18:42
If RGB works better, maybe the problem is color conversion? Have you tried all the setting combos in HUFFYUV? Normally HUFFYUV works well for capture, & the big bottleneck is getting the info on drive(s).

For capture codecs, might try mjpeg like PicVideo, or even a high data rate wmv (or other mp4 type) capture? If your prob is writing capture data, these offer more compression & so less data to write.

Otherwise, might want to look for capture optimization tips in this forum, stickies, guides etc.

LocalH
19th August 2005, 20:52
I'm wondering why you're capturing to Huffy - doesn't that card capture the raw ATSC stream like most low-cost HD capture cards do? If so, why not just capture straight to a transport stream (.ts) and then extract the raw MPEG-2 from that? There is no benefit in decoding an MPEG-2 stream and then encoding it with Huffy, unless you are doing processing to the stream with Avisynth and then planning to encode it with a multi-pass codec.

Xesdeeni
22nd August 2005, 14:49
If RGB works better, maybe the problem is color conversion? Have you tried all the setting combos in HUFFYUV? Normally HUFFYUV works well for capture, & the big bottleneck is getting the info on drive(s).I thought that's what HuffYUV would give me. But it appears the actual compression overhead is too much for this machine (AMD 2600+). Is HuffYUV less efficient on an AMD processor?For capture codecs, might try mjpeg like PicVideo, or even a high data rate wmv (or other mp4 type) capture? If your prob is writing capture data, these offer more compression & so less data to write.I thought about trying a motion JPEG codec, but there don't appear to be any free ones.Otherwise, might want to look for capture optimization tips in this forum, stickies, guides etc.I would guess that if the uncompressed capture works most of the time, the capture itself is pretty optimized. But something odd appears to be happening as data is moved around or compressed.


I'm wondering why you're capturing to Huffy - doesn't that card capture the raw ATSC stream like most low-cost HD capture cards do? If so, why not just capture straight to a transport stream (.ts) and then extract the raw MPEG-2 from that?I'm trying to capture some analog video...Xesdeeni

LocalH
22nd August 2005, 16:16
Ah, so you're not actually capturing HD video. My bad, I saw "FusionHDTV" and completely missed the words "analog video" =P

Xesdeeni
22nd August 2005, 16:51
I have the best of intentions--converting VHS tape to DVD...death to analog! :-)

Xesdeeni

mic
22nd August 2005, 18:54
@ Xesdeeni

You really shouldn't be dropping any frames doing video capture, your cpu is up to the task, so I wouldn't worry about that. The biggest prob I see at the moment is presented here:
http://www.digitalconnection.com/Support/cn_fusion_1.asp

At the bottom of the FAQ it says analog capture isn't possible. Reading other Q/A, it appears it works a bit differently then reg TV Capture cards, and I suspect getting it to work for analog capture, if it's possible, will require a bit of trial and error.

RE: the color space used & compression... If the card is producing an RGB overlay, & that is what's being captured, my guess from your 1st post would be a delay while RGB is converted to YUV -- HUFFYUV excells because it doesn't convert to RGB, but captures the YUV from a regular TV broadcast. I don't know how much different settings will help, but only thing lost is time giving those settings -- or other codecs -- a trial run.:)

If you search the forum you'll find a few free codecs listed, as well as those on the Download page. PicVideo offers a trial to see if it'll work for you.

Uncompressed RGB capture does produce an awful lot of data to write, manage, and store, but ideally I think your PC might handle it without drops, so the only thing lost trying to optimize your system for capture would be the time it took. It might or might not help really, but since your hardware wasn't designed for analog capture, I can just guess at things you might try. :)

Xesdeeni
22nd August 2005, 19:31
You really shouldn't be dropping any frames doing video capture, your cpu is up to the task, so I wouldn't worry about that....Uncompressed RGB capture does produce an awful lot of data to write, manage, and store, but ideally I think your PC might handle it without drops...Based on a great deal of experience pushing the performance envelope about 10 years ago, I'm guessing that my issue with raw RGB is due to the hard drives. While they have more than sufficient performance, there is (or at least used to be) an occasional self adjustment called a "thermal recalibration." This had to be done periodically to ensure the drive continued to function properly. However, for the duration of this thermal recal, the drive could not write data to its platters. If a transfer occurred during this time, and if it exceeded the available buffers (drive and system), data would be lost. Our first non-linear editing systems, which did real time capture and playback from a hard drive using the first generation of motion JPEG chips would suffer if a thermal recal occurred. In some cases, faster drives were able to recover quickly after the recal, and there were drives that were offered as "a/v ready" that tried to mask the effects. I assumed the problem I am seeing is similar, but at this higher tier of demand.The biggest prob I see at the moment is presented here:
http://www.digitalconnection.com/Support/cn_fusion_1.asp

At the bottom of the FAQ it says analog capture isn't possible. Reading other Q/A, it appears it works a bit differently then reg TV Capture cards, and I suspect getting it to work for analog capture, if it's possible, will require a bit of trial and error.As I said, it's functional. And I've recorded 10s of minutes, usually without much frame loss. But in 30 minutes, I get 10s of frames dropped, and I'd like to eliminate this. I had thought that HuffYUV would move some overhead to the CPU, while cutting down on the data to the drive. This should have taken care of the dropped frames, but it didn't.

Xesdeeni

mic
22nd August 2005, 20:20
"there were drives that were offered as "a/v ready" that tried to mask the effects."

High speed SCSI AV drives worked without interuption -- still have one of these insanely expensive IBM buggers around. Think it cost something like over $1000 for 8 or 10 gig back then. :scared: But then again worked with ISA mjpeg cards. :p

Currently though, shouldn't have much prob with throughput nowdays, even uncompressed RGB, & wouldn't suggest trying optimization if you weren't having prob., & if I didn't suspect that moving data from overlay window to disk was already slowing things down.

"I had thought that HuffYUV would move some overhead to the CPU, while cutting down on the data to the drive."

Actually you should have next to no cpu overhead unless you're going to one of the mp4 type codecs. That said, if you want to write the least possible, try mpg2 or mpg4.

Boulder
23rd August 2005, 07:01
I thought about trying a motion JPEG codec, but there don't appear to be any free ones.
IIRC ffdshow/ffvfw has one.

Try to crop the bottom garbage (head switching noise) the VHS tape has during capturing. I recently noticed that it can help a lot.