DV codec: coder or decoder?

[arnie.d]

Hi,

When I capture DV from my camcorder does it matter which DV codec is installed on my system? I mean does it actually code the video and audio when it's captured or is that done by the camcorder while filming and is it merely being transferred with capturing? Is the installed codec only for playback?

[Guest]

When I capture DV from my camcorder does it matter which DV codec is installed on my system? Only for subsequent editing/encoding.

I mean does it actually code the video and audio when it's captured or is that done by the camcorder while filming and is it merely being transferred with capturing? The "capture" is a data transfer process; the encoding is done in the camcorder.

Is the installed codec only for playback? You can edit and re-encode to DV also, if you wish.

[bb]

The codec inside the camcorder matters - but that one you can't change! The transfer via firewire does not change anything in the bitstream, it's just a copying process (you may call it "streaming" as well). In terms of quality issues the DV codec on your PC comes into play after the capture process is done.

Edit: oh, Donald was faster...


bb

[arnie.d]

OK.
But if I want to open a DV avi with virualdub I must install a dv codec otherwise virtualdub can't read the file. So I install the codec, open the file and cut some frames in the movie. Then I save the edited avi and use direct stream copy or I use huffyuf to compress. Does the DV codec I installed to read the avi inlfuence the quality of the edited avi in any way?

[communist]

You can use latest VDub (1.6.10) - it comes with a DV Decoder. As long as you only do DirectStreamCopy (and do simple cuts) no quality is lost as its still all just a copy & paste process. Its not really recommended to decompress it to HuffYUV for this reason as DV is pretty easy to edit and work with.

The installed (or VDub's internal) DV Decoder is only used for displaying the bitstream, when you apply a filter / transition you will have to specify which Codec to use for recompress (if you want to do that in VDub you'll have to install a VfW DV Codec as the Windows internal DV codec is not listed in VDub).

[arnie.d]

So when I apply a filter in virtualdub is it a good idea to recompress to huffyuf? Huffyuf is better then recompress with a DV codec again right? I guess uncompressed is best?

[communist]

Depends on what you intend to do with the output file. Do you plan on recording it back on a MiniDV tape? If so its better to recompress to DV. If you plan on encoding to XviD / DVD etc. you should use AviSynth (http://www.avisynth.org/) for filtering and load that script in your encoder.
Unless you want to use very very slow filters / scripts you dont really need HuffYUV for this purpose.

[arnie.d]

I plan to encode to m2v using CCE.

[bb]

So when I apply a filter in virtualdub is it a good idea to recompress to huffyuf? Huffyuf is better then recompress with a DV codec again right? I guess uncompressed is best?
Many DV applications have a "smart render" mode: only parts with real changes like transitions etc. get recompressed, whereas the rest gets copied losslessly. For perfectionists a lossless method is preferred, either by saving to an intermediate format like Huffyuv, or by frame serving (e.g. through AviSynth).

Uncompressed is not better than lossless compression. It's even worse, because it takes more disc space, and processing is slower.

By the way: did you read the "DV to DVD" guide?

bb

[arnie.d]

Yes I read the guide.
Uncompressed takes more space and is slower but the picture quality is the best isn't it? If I make a laserdisc transfer and denoise and sharpen the DV avi it's best to save it uncompressed than recompressing it I think.

[lilhobo]

wait a minute, DV is lossy still, right???

My 2 cents,

1. if u have fast (and large) HDD, then use uncompressed: only I/O is the limiting factor
2. if u have fast CPU then recompress losslessly, since the CPU is the limiting facttor and needed to re/decompress.

EDIT: leaving it uncompressed means u save the time to recompress to another codec.

so why is DV considered lossy??

[communist]

Yes I read the guide.
Uncompressed takes more space and is slower but the picture quality is the best isn't it?
But you can save your way to the uncompressed file and filter it with AviSynth which has a lot of really excellent external plugins.

so why is DV considered lossy??
Because it is lossy?! The output is not bit-identical to the output unlike with lossless compression.