Clear my confusion please

[lilhobo]

When you record to DV tape its already in DV format???

Can you lose quality due to tape wear??

When you transfer to PC its a straight transfer?? No encoding??

the decoder on the pc plays it according to its quality, but unless the file if modified, it cant be different to the one on tape??

:stupid:

[Video Dude]

When you record to DV tape its already in DV format??? Yes.


Can you lose quality due to tape wear?? It is possible that the tape can develop drop outs.


When you transfer to PC its a straight transfer?? No encoding?? 1:1 Transfer via 1394 port.


the decoder on the pc plays it according to its quality, but unless the file if modified, it cant be different to the one on tape?? The file is not changed by the codec. It just decodes for playback. Video quality will differ depending on which DV codec you use.

[Blue_MiSfit]

This is true. Note that when you edit DV, the quality does not degrade.

One thing I never understood is if the camera records in DV, why does it make a difference what codec you use to capture the DV? This seems to imply that there actually is some re-encoding happening when you transfer from tape to hard drive.

I know that there are different DV codecs (Avid, Apple, Canopus, MS, etc...), and that they sometimes use different chroma subsampling methods etc, but how does this work?

~MiSfit

[Video Dude]

why does it make a difference what codec you use to capture the DV?
It does not make a difference. You can choose Type 1 or Type 2, but it is still considered 1:1 in terms of quality.

What codec you use matters when you re-render the DV. Such as during an editing project you add title text over the video. The DV codec is used to re-encode the video. (For just cuts during editing, most editing software will "Smart Render" the DV and it will not be recompressed).

The codec also matters when you playback or compress to another format, like MPEG-2 or Xvid.

[bobcat56458]

Hi Blue_MiSfit, just to keep things factual, when you edit using a DV codec the quality does degrade because DV is not a lossless codec. However you will not probably notice the quality loss unless your doing 3ed, or 4th generation re-encoding, and the amount of degradation will depend on which DV codec you are using. Some degrade multi generation re-encodes more than others.

[LocalH]

This is true. Note that when you edit DV, the quality does not degrade.
Only in frames that are included in the final project without changes. Transitions, titles, and other processing filters will require decoding to apply the effect and then reencoding to put it in the final project.

One thing I never understood is if the camera records in DV, why does it make a difference what codec you use to capture the DV? This seems to imply that there actually is some re-encoding happening when you transfer from tape to hard drive.
You're not making use of any software codecs when you capture from a DV device - you're making use of the hardware codec inside your device (whether it be a camera, DV deck, or analog-DV converter). You only make use of a software codec once the video is already on your hard drive, for both decoding and reencoding.

I know that there are different DV codecs (Avid, Apple, Canopus, MS, etc...), and that they sometimes use different chroma subsampling methods etc, but how does this work?
Some codecs use point-resizing for the chroma (more accurate to the data stored in the DV stream and thus capable of handling more generations, but less visual quality), while some codecs interpolate the chroma to reduce stairstepping (which can also cause additional degradation as you go through further generations).

Video Dude:
In your first sentence, you're referring to the container, not the codec. The only difference between type-1 and type-2 is whether the audio is also included as a separate audio stream (type-2) or not (type-1). Either way, the DV stream always contains both audio and video. Type-2 takes more drive space but is more compatible with VfW apps such as VirtualDubMod (which can not make use of the audio in a type-1 AVI).

[Blue_MiSfit]

Wow. That makes sense now ;) Thanks for all the replies ppl...

Now I understand why some insist on editing DV uncompressed. No generational losses at all!

Awesome. I feel enlightened :D :D!!

[bb]

[...]You're not making use of any software codecs when you capture from a DV device - you're making use of the hardware codec inside your device (whether it be a camera, DV deck, or analog-DV converter). You only make use of a software codec once the video is already on your hard drive, for both decoding and reencoding.[...]
The camcorder's hardware DV codec is not involved in the capture process either. The video stored on tape is already in DV format.

Exception: Sony Digital8 camcorders may transfer Hi8 analogue video to the PC via firewire; in that case the video is encoded during the capture process.

bb

[henryho_hk]

..... VfW apps such as VirtualDubMod (which can not make use of the audio in a type-1 AVI).

It seems Virtualdub 1.6.16 can handle both video and audio in Type-1 AVI.

[LocalH]

The camcorder's hardware DV codec is not involved in the capture process either. The video stored on tape is already in DV format.

Exception: Sony Digital8 camcorders may transfer Hi8 analogue video to the PC via firewire; in that case the video is encoded during the capture process.

bb
Well, yeah, but the video went through the codec while being written to tape, and also for cameras with analog passthrough.

[bb]

It seems Virtualdub 1.6.16 can handle both video and audio in Type-1 AVI.
That's true; the more recent VirtualDub versions can handle DV type-1.

bb

[theReal]

Now I understand why some insist on editing DV uncompressed. No generational losses at all!

But only if you re-edit an already edited file. If you load your first generation DV into an editing program and you add for example a few fades and titles and some color correction and then you go back to DV (i.e. back on tape) you will have exactly the same output as if you go through an uncompressed step, then edit and then go back to DV.
If you're only going straight to DVD out of the editing suite then of course you avoided one generational loss. However I doubt it will make much of a difference on your final DVD...

[LocalH]

Yeah, that's more of a workflow issue than a specific DV issue - if you're going straight from your final edited project to another format, then it doesn't really matter so much, but if you render back to an interim DV file before encoding to your final format, then you've lost a generation.

[bb]

As long as you don't edit and reencode the same scene over and over again, I wouldn't make myself a headache with generational losses - it's simply not worth it. Better avoid the headache by using a good camcorder, and following the rules for taking a good shot in the first place.

bb

[Fizick]

please rename this thread to more informative.