mpeg2 6000kps DVB convert to xvid

[drewzor]

deleted

[jimmalenko]

I'm using Virtual Dub Mod and deinterlace - resize to 512x288 and attempting to save a file around 350mb
.The mpeg2 file is 1.83gb and what ever settings i use I cannot get the file size down passed 700mb without really shagg'n the footage..

Can you guys suggest what i could do to reduce the file size while maintaining a resonable video quality?

Maybe try AutoGK - very easy to set horizontal frame size, desired output file size and it will also deinterlace.

Two) my computer and programes like avicodec do not report the duration of mpeg files, is there anything i can do about that?

AVICodec is for AVIs, primarily. The latest GSpot Beta (V2.52) can read MPEGs. There's also MediaInfo, and a few others also in the tools section under video Identifiers (or similar).

Three) I have notice that i have to save the audio stream and then mux it back to keep sound sync, is this normal and is this how i should deal with it..

I don't deal with DVB streams, but it don't seem normal to me. Almost sounds like a timecode issue.

Bonus round question: I was given a video that was already converted to avi with the audio out of sync, could someone please refer a previous post for a solution to fix that?

Forum search "audio out of synch". Depends on the type of synch and how anal you want to be about it as to how to go about fixing it.

[drewzor]

deleted

[jagabo]

You need to use a light temporal smoother to get rid of the background noise.

I did a quick test with:

Deinterlace (blend)
Resize (512x288, lanczos3)
Sharpen(15)
Temporal Smoother (1)

That got decent results at 800 kbps VBR. That's about what you'll need to get 45 minutes into a 350 MB file along with 128 kbps. That audio bitrate is lower than I would normally go but it's acceptable for dialog. I wouldn't normally use blend deinterlace either but it works fine for that type of video. The sharpen filter helps restore some of the sharpness.

[drewzor]

deleted

[jagabo]

With VirtualDubMod set the filters up the way you want. Then go to the Xvid configuration dialog and select Twopass 1st Pass and Save as AVI. During the first pass the codec is only examining the video, it's not saved to the AVI file. When that's done go back to the Xvid settings and select Twopass 2nd Pass, set the bitrate or target size and Save as AVI again.

[drewzor]

deleted

[manono]

How do you know that? Did you save the first pass AVI as a playable AVI? If yes, did the second pass AVI hit the size you wanted? If yes, then you could have used a higher resolution, better quality audio, less filtering, and/or all of the above, and still have gotten a very nice looking AVI. Although there's nothing wrong with getting a result at 93% of max size, in my opinion it doesn't let the MPEG-4 compression really shine. It's often recommended that you aim for 60-75% of max size.

[drewzor]

deleted

[jagabo]

The size of the first pass is irrelevant. Xvid uses a Constant Quantizer of 2 (a high constant quality) to evaluate the video during the first pass. The file will come out to whatever size it does.

The size after the second pass is determined by the requested Target Bitrate:

bitrate * running time = file size

If you want a smaller file use a lower Target Bitrate or Target Filesize.

There is a condition where the requested file size/bitrate may not be met. On the Advanced Options dialog, under the Quantization tab, you can set Max and Min Quantizer values. The defaults for Min a 1 and Max are 31. Normally you shouldn't change these. If you do change these the codec may not be able to produce files of the size you want.

[drewzor]

deleted

[manono]

Also my big expectation is to keep a decent video quality even when played at 200% or 1024x576

1024x576 is 4 times the size of 512x288 (which is a pretty low resolution, and lower than I'd ever use for a widescreen source)

even if you do a single pass @ 150 bit rate quant @ 4

You do it for either a bitrate of 150, or you do it for quant 4, but not both at the same time.

...it comes out unbearably distorted !!@620Mb!!

Distorted how? Like really lousy quality, all blocky and blurry, or distorted as in bad aspect ratio? Is the audio in that 620 MB AVI? If so, what kind? WAV audio? Open it in GSpot if you don't know.

I set the target size etc and it cannot get lower then 612mb.

If that's really true, did you by chance install a newer XviD on top of an older XviD codec? Doing that can lead to unpredictable sizes. When getting ready to install a newer version, you're supposed to uninstall the older version. But if there's WAV audio in there, that could also explain the big size and low video quality.

I dont think anyone realy knows how to convert with xvid properly from Hidef DVB.

Forgive me for being harsh, because I know your statement comes out of your frustration, but the only one in this thread that doesn't know how to use XviD is you. Also, there's a big difference between capturing a TV show for reencoding to XviD, and using the DVD as a source. Captures, even Hi-Def ones, may have noise not seen on the DVDs. Your source may be a lot less compressible than the source for your download. Did you even try jimmalenko's suggestion earlier in the thread about using AutoGK?

[drewzor]

deleted

[manono]

Hi-

Audio is ac3 and left that way for conversion (my understanding was that xvid converts to mp3 audio track??)

XviD is a video codec, and has nothing to do with audio. However, if the AVI contains audio, then more than once the unwary have wondered why the file size wound up so large only to find that their nice AC3 audio had been converted to LPCM WAV audio by the encoder. So, please make sure it's still the original AC3 audio you have by opening up the nasty looking 620 MB AVI in GSpot to check the particulars.

Yeah, if you installed XviD over XviD, then it's best you remove all traces of it and install it again.

I just want to keep it the drive without having to waist nearly a gig for 40-50mins of mythbusters..

At 512x288, you shouldn't have to waste nearly that much space. The 350 MB figure you're aiming for sounds fairly reasonable for 45 minutes of video. Again, though, it depends on how compressible the source is, and what kind of audio you're winding up with.

I have used AutoGk previously but not for DVB rip.

As far as I know, AutoGK does just fine with Hi-Def caps. I don't know at what framerate you're capturing these things, but if 50fps, then you might have to go into the Hidden Options (CTRL-F9) to reduce it to 25fps, if you want. That's something else you should check with GSpot.

[jagabo]

I thought there was a bitrate and then a variable "block" size of pixels via quant..

Target Quantizer encoding is for constant quality. The quantizer value is essentially how much detail gets thrown away. The lower the quantizer the the higher the quality. You select the quality you want, every frame is encoded with that quality, and the file comes out to whatever size it does.

Constant Bitrate encoding uses the same bitrate for the entire video. You know how big the file will be (excluding audio) but you don't know exactly what the quality will be. To get good quality for the entire video you need to use a high bitrate, thereby wasting bitrate on scenes that don't require it.

Audio is ac3 and left that way for conversion (my understanding was that xvid converts to mp3 audio track??)

VirtualDubMod saves audio as uncompressed PCM when reading from MPEG sources -- even if Direct Stream Copy is selected. This probably explains why your files keep coming out larger than you expected. 45 minutes of uncompressed PCM audio is about 500 MB. You have to enable full processing mode and manually select an audio codec and bitrate.

[drewzor]

Deleted

[jagabo]

Glad to help out.