How best to capture

[colinbr]

I have a VHS tape which I would like to capture at the best possible quality. The issues of quality and codecs and not being able to playback captured files on other PCs is thoroughly confusing me!

I have a G450eTV and am running Windows2000 with FAT32X.

To begin with I'd like to capture a "master" copy of the tape (about 10 mins long) which is as high quality as possible. The Matrox Hard Drive metric program says that my PC is too slow to capture YUV2 (19M/s) so I will have to use MPEG2 using PC-VCR, or possibly use the supplied ULEAD Media Studio 4 to capture, or maybe Virtual Dub.

I don't mind which program I should use as long as the captured quality is as good as possible, and that if my G450eTV blew up tomorrow I would still be able to read and use this master capture file.

Can I get a much improved MPEG2 capture in PC-VCR by tweaking the parameters?

Is there a page somewhere which explains what the various options are for capturing, what codecs they use, whether they need the G450eTV hardware to be present, what file formats they produce (e.g. AVI, MJPEG MPEG2 etc).?

Sorry for all the questions but this is all pretty confusing!

Thanks

Colin

[Frank Marshall]

Hi Colin,

Looks like you should investigate the PICvideo MJPEG codec. Do a search here and you'll find it will give you most of the features you're after. The only problem is that you won't be able to play a PICvideo encoded file on another computer unless you install the codec there too. MPEG-2 or high-bitrate MPEG-1 is probably your best bet for high-quality video that is readable on most PCs but unless they are I-frame only encodes, editing the footage will be difficult.

I should also mention that to use other codecs than the supplied MPEG-2, you'll have to capture with an application other than PC-VCR remote. You could use VirtualDub or AVI_IO.

Regards,

Frank

[colinbr]

Thanks Frank,

I'll investigate the PICvideo codec.

I forgot to mention that the video I'll be capturing has a lot of crash edits where the adjacent clips are not in frame sync - I'm not sure how the card will process these but I suppose it is possible that I may end up with a partial frame at each "join" in the capture which I may have to remove in Media Studio. It also has a poor quality music soundtrack which I want to replace in its entirity.

All of this means that I will have to do some amount of editing, which prompts the following question: when I output the final cleaned-up video to a master AVI (or MPG or whatever) will I get a degradation in the picture quality? I'm thinking of the sort of thing which happens when you repeatedly load and save JPEG still images in Photoshop where each "save" pushes the image data through the JPEG compression algorithms and progressively degrades the image - does the same apply to reloading and saving video files in Media Studio? Or do editing programs have the "intelligence" to know that they can save unmodified parts of the project without compressing/degrading them further.

Perhaps to be on the safe side I should archive BOTH the original capture file AND the tidied-up file too.

I know that there are a variety of MJPEG codecs and you must have the matching one loaded onto your PC to play a file encoded with same codec, but does the same appy to the MPEG2 format - i.e. are there a number of MPEG2 codecs or is this a rigidly defined file format that should be playable anywhere?

Finally, it strikes me that if you NEED the G450eTV hardware to play MPEG2 files captured on this card, then it would be a bad move to use the PC-VCR MPEG2 capture for any footage that you wanted to keep - if the G450eTV died then you may be unable to play back the files at all!

Colin

[Frank Marshall]

Hi Colin,

Whenever you capture and render video with a MJPEG codec it will undergo some degradation as MJPEG is a lossy codec; it throws out information in order to compress the video frames which is why one tries for the least compression possible. This is why many Marvel users here capture using the HuffYUV codec, it is a kind of raw video codec that has virtually no degrading effect on the digitised footage. This is about the limit of my knowledge in this area so best you do a search here to find out more. BTW, HuffYUV is free whereas PICvideo costs about $25-odd.

I use Premiere but I'm sure MS Pro will also only recompress the video segments that need rendering such as transitions and filters so yes, that "intelligence" is there. Of course if you capture with MJPEG and then save to MPEG-2 the entire project will be rendered to the new format and there will be some degradation. Fear not, if done properly (i.e. minimal compression with a quality codec) the results can be very satisfying.

For MPEG-2 compression most folks seem to agree that TMPEG is the ant's pants and it's free to boot. Because MPEG-2 is the compression algorithm used with DVD and satellite video you'll find it is a very portable format that isn't hardware dependent, i.e. you don't need a G450TV to playback MPEG-2 files.

Cya!

Frank