Capturing with Xvid

[Northstar]

Hi.

I just bought a tv capture card the other day, Winfast 2000 XP and i have a couple of questions.

First of all im capturing from digital satelite tv with xvid with the winfast wizard thing, i set xvid to capture at 1 pass CBR 5000 and get around 2 gig captures for a 80-85 minute film, i set the resolution to 640x480 (anything below this looks crappy imho), i dont use any audio compression and thats captured at 44100hz.

After capturing i run it through virtual dub to compress the audio and video. I use xvid again with 1 pass quantizer and set it to 3 or 4, and very high quality in advanced, i compress the audio to 44100hz/128k.

Is this the correct way to do things?

The only problem i seem to have is getting the size to a set amount, thats something i dont quite understand yet... any advice?

Thanks.

[DJRumpy]

There is not a 'right' way to do things. It's more a matter of preference (although there is a wrong way to do things ). Your method will work just fine. If your after better quality, consider the Huffman codec, as it's lossless, while DivX is not. Just be aware that the compression ratio for Huffman is about 2.1:1, so yo will see a substantial increase in size for the capture file.

In regards to your size question, for DivX, you use a bitrate calculator to find out exactly how large your output will be (Look in the TOOLS section). It will give the the Kbps. Set that to whatever the bitrate calculator tells you. Set this the Kbps according to the length of your video, and the media your placing your video onto (the space available). Just remeber to account for your audio in your calculations (some calculators include audio bitrate, some don't...try to find one that does).

[non-linear]

consider the Huffman codec, as it's lossless, while DivX is not. Just be aware that the compression ratio for Huffman is about 2.1:1, so yo will see a substantial increase in size for the capture file.

Don't you mean the Huffyuv codec? I've never heard of one called Huffman.

[Northstar]

Ok thanks for that, i will just stick with xvid though, dont have a clue with divx what im doing, the picture always goes very jerky with divx on fast moving scenes so i gave up with that. The file size issue of getting it too low at around 600-ish mb or too high at 750-ish mb dosent matter so much, i did want to put this stuff on cdr, but i do have a dvd writer so i can put a few on each dvd... like the Lemon Popsicle videos which i want to back up, i can fit all 8 of them (when i get them, i only have first 2) on one dvd maybe, if i convert make them all around 550-ish mb each and with them being 20 years old im sure you wont be able to tell the difference.

[feenix]

Here's my way to encode with xvid and get the desired file size you want. This will work whether you've captured in xvid or uncompressed

1. Extract the audio with vdub (save wav)
2. Convert the extracted wav file to mp3 using Besweet, or whatever audio encoder you use
3. Make a note of the resultant mp3 file size (roughly 100mb per 2 hour movie depending on the bitrate you choose - I find 128 adequate) and subtract that from 700 (cdr size)
4. open the avi in vdub and compress with xvid 2 pass 1st pass; select No audio and Save Avi.
5. After a couple of hours or so and the 1st pass has finished, open xvid again and select 2 pass 2nd pass. You will then notice that there is an input box for file size so just enter the difference between the mp3 size and 700. Select any filters that you want (resize etc) and make sure the audio is set to No audio again then Save Avi
6. After another couple of hours and Vdub has finished encoding you will have an avi for the video and an mp3 for the audio created earlier.
7.Multiplex the avi and mp3 with Virtualdub_MP3_Freeze and then you will have a working avi at as near as 700mb as damned it

Now this works for me but you may have to adjust some of your settings as per your particular PC

There are other ways of dealing with the audio but it must be done first to get an accurate file size.

Hope this helps

[lordsmurf]

consider the Huffman codec, as it's lossless, while DivX is not. Just be aware that the compression ratio for Huffman is about 2.1:1, so yo will see a substantial increase in size for the capture file.

Don't you mean the Huffyuv codec? I've never heard of one called Huffman.

Huffman is the basis for HuffYUV. Huffman YUV encoding.

[RabidDog]

huffman is a type of compression .. like zip... probably huffman invented it...

[DJRumpy]

Correct It is the same compression method used by ZIP.

the picture always goes very jerky with divx on fast moving scenes

This is most likely due to dropped frames. Does your software report the number of dropped frames? Capturing to DivX, or XviD is processor intensive, due to the compression ratio. A capture to divx might run anywhere from 1 to 4 gigabytes. A Capture using a huffman codec can run from 20 to 40 Gigabytes on average, depending on the length of your video.

If your software doesn't report dropped frame information, then I'd suggest you give VirtualDub a try for capturing as well. It will report the drop frame rate while your capturing. If you find it's dropping frames, consider lowering the resolution.

I am a bit curious, as to why your re-encoding the same source material, using the same codec, twice. If your trying to reduce the size of your capture, while keeping it in the DivX format, then consider using multi-pass to process it. This will allow you to use lower bitrates, while still retaining as much quality as possible. Start in the area of 1200Kbps, with 2-passes or more.

To use multipass, open VirtualDub, select the VIDEO | COMPRESSION menu, and then the DivX codec from the list. Click the CONFIGURE button, and on the first tab, select "Multipass, 1st pass" for the Variable Bitrate Mode setting. Ensure the 'Write MV file' is enabled on the Bitrate Control tab. You can also change the path here to point to the same directory as your AVI file. This makes cleanup later easier (your less likely to forget to delete the BIN and LOG files )

I would use 'Slow' on the performance tab, or slowest if you don't mind the wait. I usually don't notice much of a difference between the two though. When you save your AVI, it will create a BIN file, storing information from the first pass. When it completes the first pass, enter the codec compression settings again, and change the Variable Bitrate Mode (again, on the Bitrate Control tab) to 'Multipass, nth pass'. Ensure the 'Read MV file' is enabled. You should also select 'Update Log File'.

Save your file again. The additional passes will reduce or eliminate any macroblocking from scene changes, fades, or fast motion. This assumes they are not in your source from the initial capture of course.

Once your satisfied with your output, you can delete the LOG and BIN files. Do not delete them until you are completely satisfied with your output.

[Northstar]

lol you all make it sound a bit long winded.

Do i really need all these passes to get good quality?

I find if i do it the way i said earlier with xvid everything looks pretty good, i cant (rarely) see any macroblocks, if the file sizes i get are 1 gig i dont mind so much as i will put them on dvd instead of cdr.

The main reason is that i dont really want my computer out of action for hours at a time, the way i do it keeps my pc out of action for the length of the thing im capturing plus another 1 and half hours max for compression.

Thanks for all your suggestions though, i will be sure to try them out once i get into this capturing lark more.

[Gazorgan]

Don't marry yourself to a 1 Disk encode. This is fine for 1 hour TV shows, but generally sucks horribley for 90+ minute videos in anything above 320x240.

[feenix]

Gazorgan,

While that is certainly true for mpeg1/2 it definitely isn't for xvid/divx

[DJRumpy]

Yes. DivX should look ok at 1GB, although that's pushing it for a single pass (assuming movie length here..if it's a 60 minute show, it's more than enough).

Yes, the second pass can make that much of a difference. You can basically setup VirtualDub to batch the jobs, so you set it up before you go to bed, and wake up with a finished avi. It's very simple. When you selecting FILE | SAVE AVI, before clicking OK, make sure you put a check in the 'Don't Run This Job Now' checkbox. It will return you to the GUI. Immediately go back in and setup your second pass settings, and select FILE | SAVE AVI again. Same as before, put a check in the 'Don't Run This Job Now' checkbox and click OK.

From the FILE menu, select FILE | JOB CONTROL. You should see both passes listed. Just click the START button, and leave it until morning.

It may sound a bit complicated, but it's very easy in practice.

[Gazorgan]

*feenix

Really? I'd be delighted to see a 120 minute DivX in 640x480 on a single disk. No artifacts and 128k stereo minimum please.

Can't be done, don't try and sell it. And you've never seen one either.

[DJRumpy]

For a 120Min move, you would more often than not, see a two disk set, or 1.4 GB (enough to fit on two CDR's).