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Discussion Starter · #1 ·
What is the consensus here for best quality video capturing? Is it better to use a tuner/capture board that encodes the video straight to MPEG-1 or MPEG-2? Or is it preferable to use a card that captures "uncompressed" video, then later convert it to the desired format for DVD, VCD, or whatever?


What are the disadvantages to capturing video directly into MPEG1/2 format? As far as advantages I can think of two: does not require huge amounts of hard drive space to store and edit uncompressed video captures. And convenience.


What are the advantages to capturing as AVI? People talk about editing AVI and then encoding it to MPEG, DiVX, or whatever. But can't you also edit a captured MPEG-1 or MPEG-2 file?


Video gurus please explain these issues to an HTPC noob.
 

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If you can capture in high-quality uncompressed, that should give you the greatest flexibility for converting to different formats, and trying different MPEG encoders.


If you don't have that luxury, then capturing in the precise compressed format you intend to output is best, to keep the loss to a single generation.


Raw AVIs are not lossy, so it's easier to edit with them without creating further degradation, and then output or convert the final result to MPEG. Editing MPEG directly is possible, but it's difficult to do without further loss, unless its cuts only. Some lower-end DVD apps will give you this basic cutting ability, by allowing you to clip your MPEG streams at in and out points, and string these pieces together.
 

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Discussion Starter · #3 ·
So, you can edit MPEG files without causing further quality loss than the original compression, but the only edit you can do is deleting frames. Like for example taking out commercials. Do I understand this correctly?
 

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Cutting frames, and maybe cropping would be ok since they don't effect the picture quality. If you wanted to run some kind of filter (eg resize, deinterlace, sharpen, etc), you would want to run that on an uncompressed file, not on one that is already encoded. Encoding a file and then processing it is like deliberately messing up a file, then trying to clean it (ie garbage in garbage out)
 

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Discussion Starter · #5 ·
I understand. The thing is I'm having trouble deciding which tuner/capture board to buy. I don't need to do more than cutting & cropping of the captures, so a real-time MPEG1/2 encoder would seem to be the best choice. But from what I hear, the FlyVideo has the best picture quality, and is very good at rejecting noise. This is especially important as I'm watching plain OTA TV broadcasts. But the FlyVideo doesn't do RT MPEG-2 encoding.


Which card do you recommend?
 

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Wish I could help, but I'm not familiar enough with the different options available to offer much guidance.
 

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I did both ways for a long time and I found the best method is using Vdub capturing video to Huffyuv and 44/16 PCM for audio. That's about 170mb/min but as said above you have the flexibility of converting to whatever format you want (which is usually 1000kbps Divx5 & 192kbps Lame MP3 for me).


For my purposes & HD space I don't record entire shows, usually small things such as Conan O'Brien skits and musical performances. If I did use it as a PVR to record hous of material I'd open up the program that came with the card which records in mpg2 and is programmable


mbaxter- I may be wrong but can't you get a seperate program like PowerVCR that uses software rather than hardware for MPEG-2 encoding?
 

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Discussion Starter · #8 ·
After listening to everyone's advice and researching the matter, I decided that the superior PQ of the FlyVideo cards was more important than their lack of real-time MPEG-2 encoding, so I ordered a FlyVideo 3000. Then I read Scotty L's post. Looks like I may be able to have my cake and eat it, too!


I'll definitely give PowerVCR a try once my FlyVideo arrives and post the results here. I have a P4 2.53GHz with 512MB RAM so I would think the machine could handle real time encoding, but then what do I know. Eager to find out.
 

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mbaxter just a word of advice be sure to do a comparison between the tuner on the card vs an outboard tuner (VCR or digital cable box). There was a little less noise using a VCR (and MUCH better audio than my Asus card) so I used the VCR from then on. The FlyVideo may give you better results though.


As for PowerVCRII, I used it on my P2.4 and the mpeg-2 captures were fantastic. I'm sure you'll love the software. Plus if you're willing to pay $100 for the Deluxe they'll throw in PowerDVD.


Just be sure when you capture video don't delete or rename the .PLT file it creates alongside of it, PVCR needs this to play the videos. If you want to rename them you can either do it right after you press stop when recording or double click them to bring up a window that will let you change it that way. I screwed over several of my captures by manually renaming the PLT's in Windows and then forgot the original name when they wouldn't play. :eek:
 

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My 2c worth...


If you are after best quality, get yourself a stock standard Bt878 based video capture card. (I use an old Avermedia EZCapture card - no tuner - very cheap!).


Use a good quality external tuner (eg: quality VCR or even better S-Video out of a set top box). S-Video source where possible!


NB: Stay away from the newer "Fusion BT878A" cards, as most seem to exhibit vertical noise bars without ground plane mods. Also the advantage of bT878 is broad software support (including DScaler for excellant PC based deinterlacing etc).


Then use HuffyUV lossless codec based AVI capture (I use iuVCR for ad-hoc capture and PVR functionality). HuffyUV provides 2:1 lossless compression so you run about 30GB per hour of captured video.


Finally use your encoder of choice for final output cut editing and compression. I use TMPGEnc to cut edit remove commercials, and compress to extremely good quality using 2 pass VBR DVD compliant MPEG2.


I have played with most of the various PVR software etc. If you want convenience instead of quality go down the PowerVCR / real time MPEG compression route. However if you want quality, stay away from realtime software MPEG compression.

(Yes I have my own licensed PowerVCR, but no longer use it).


No matter what your processor speed, realtime MPEG2 compression is based on compromising compression quality for the algorithm to do realtime. For best final quality you will want 2 pass VBR encoding, which of course cannot be done realtime.

NB: If best quality MPEG2 was achievable in software at realtime speeds, then excellant quality MPEG2 encoders (like TMPGEnc) wouldn't take several hours to encode a 30 minute clip!


Finally, at all costs avoid double lossy compressing any source (ie: lossy compressed capture, then lossy re-compressing later). If you do this, quality loss will be severe (it takes many more bits to compress previous compression artifacts, than clean original video, so quality goes down the toilet!).


Also, note that you cannot (easily) do frame accurate editing with an MPEG2 stream. You can only cut edit at each full "I" frame intervals in the MPEG2 stream.


If you want to remove commercials with frame accurate cut editing you want to capture as AVI (HuffyUV lossless codec recommended).


Just based on my experiences over the last few years.


Greg
 

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Discussion Starter · #11 ·
What a wealth of information! Guys your help has been invaluable. I'm looking forward to putting your advice to real life use.
 

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Hey KoolKiwi, is 2-pass VBR better than 8Mbps CBR? I know that you can get the resulting files smalling using the 2-pass VBR method, but if I'm encoding a 1 hour capture that I'm burning to DVD, wouldn't CBR encoding be quicker and give the same quality as 2-pass VBR?
 

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In my experience Taz VBR can be flaky when trying to go forward or background through the timeline when playing (ie- the video gets out of sync with the audio or the video just doesn't want to display again). Though the resulting file size is smaller I prefer CBR because it seems more stable when decoding.
 

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Quote:
Originally posted by taz291819
Hey KoolKiwi, is 2-pass VBR better than 8Mbps CBR? I know that you can get the resulting files smalling using the 2-pass VBR method, but if I'm encoding a 1 hour capture that I'm burning to DVD, wouldn't CBR encoding be quicker and give the same quality as 2-pass VBR?
Hey Taz,


The point is that VBR will give better quality results at the same overall file size (ie: same average bit rate) as CBR.


This is because more bits are allocated to improve compression quality of the complex fast motion frames, and less bits to static / low motion frames.

Hence the need for 2 passes (for proper VBR processing), 1 to allocate the bit rate distribution to achieve the desired file size / average, and the 2nd pass to actually compress.


You will find that DVD's are mastered using VBR for this very reason. Best overall quality for the available file size!


Obviously you can also use VBR to obtain similar results at smaller file sizes, however my desire is for best possible quality for capturing and mastering to DVD-R discs.


Using VBR I can get 3x 42 minute episodes (1 hour programs before commercials are removed) onto a single DVD-R disc with menus, using a VBR average bit rate of 4100Kbps.


NB: The bit rate required is also highly dependant on the quality of the original capture. Hence I start with S-Video / HuffyUV lossless capture, then do a once only compression with TMPGEnc 2 pass VBR.


If I need a higher bit rate for lesser quality source, I drop back to 2 episodes per DVD-R disc at around 6200Kbps average bit rate.

Scotty:


I have never had any problems with VBR, as you describe. Perhaps you are trying to compress to too small a file size for the resolution, or perhaps your source files are not the best quality?

What tools were you using for your capture / VBR compression?


Greg
 

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Cool, I am re-encoding (from the original source) using 2-pass VBR now. Man it takes a LOT longer this way, but if it gives better results, I'm all for it.
 

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rgathright,


If you can do a lossless capture in extremely HQ, then it sounds as though the non-realtime software encoding may still deliver the best results, regardless of whether any editing is involved. It seems as though better PQ can be achieved if the software can crank away on the compression in it's own sweet time.


If you don't want to bother with this, then capture with the precise specs needed for burning the DVD.


BTW, I seem to recall some PQ issues when using variable bitrate encoding for DVDs specifically with the MPEG.now encoder in Ulead's Move Factory. That issue may since have been fixed though. IAC, if you're converting a raw AVI to DVD-MPEG2 in Movie Factory, you may want to try 8000Kbs constant bitrate. I think the VBR worked ok on other streams though, like SVCDs, etc. My memory's a bit fuzzy on some of this.
 
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