Is DV lossless?

[Inventive Software]

As simple as the title sounds. Is it lossless or not? I'd like to test it later on in the year if it's a lossless codec, but my suspicions tell me otherwise.

[communist]

Its not lossless. It uses DCT-compression and also applies color-subsampling (4:2:0 for PAL and 4:1:1 for NTSC).

[SeeMoreDigital]

.... Offering 5:1 compression, component video storage and records onto 6mm (¼") tape for both mini-DV and DV-Cam.


Cheers

[mustardman]

And different implementations (read codec manufacturers) provide different quality. Don't assume that they are all equal! (that also includes the hardware codecs in video cameras & DV recorders).

[Mug Funky]

there's not much lossless around, actually.

miniDV (DV25) is 25 megabits per sec

DVCPRO (i think) is 50 mbps

digital betacam is 90 mbps, and 4:2:2 - even this isn't lossless, but losses are really minimal thanks to 10-bit (ie most of the error is truncated once you get it down to 8 bpp).

i've heard heaps of people refer to DV as lossless, and i really wish they wouldn't - it's like calling 128kbps mp3 "CD quality".

[Inventive Software]

OK, thanks for the clarification! I won't ever call DV lossless ever again!!

[Malow]

DVCPRO (i think) is 50 mbps

Just correcting, DVCPRO is also 25mbps, DVCPRO50 is 50mbps

[SeeMoreDigital]

Just correcting, DVCPRO is also 25mbps, DVCPRO50 is 50mbpsJeez......

Can you remind me what the abbreviations stand for?


Cheers

[Mug Funky]

aaah, THAT's what the 50 stands for :)

hehe, i don't work with DV much.

[hendrix]

Digital Betacam uses 2.7:1 compression, DVCPRO 50 uses 3.3:1 compression and has a 4:2:2 color sampling and there's also DVCPRO HD (100mbps)

also keep in mind that consumer DV does not precisely lock its audio to its images. Audio edits may have brief silences or clicks as the sound catches up to the picture. The PRO formats (DVCAM, DVCPRO, and DVCPRO 50, etc.) lock the audio precisely to the pictures. Their audio edits are perfect and accurate.

[LocalH]

Uncompressed lossless is 27MB/s at D1 resolution (720x486). Huffyuv will decrease this quite a bit, depending on the content of the video.

DV is lossless in terms of cuts-only editing and transferring the video between devices, as opposed to analog interconnects which will always degrade the signal a tiny little bit. It's still compressed, but you can do cuts-only editing with no recompression. In the same vein, you can transfer a DV tape to your computer, send that to a second DV tape, and know that the contents are 100% identical, which is impossible to do with analog (you have to get all the way up to professional SDI interconnects to be able to approach that capability with analog baseband video). Although this could arguably be called "generationally lossless" as opposed to the more standard definition of lossless.

Also remember the chroma resolution factors into this as well. To really be considered lossless you have to use a 4:4:4 chroma encoding, otherwise you're dropping at least half of the chroma samples (assuming a 4:4:4 source in the first place).

[berrinam]

Although this could arguably be called "generationally lossless" as opposed to the more standard definition of lossless.Well, if it was called generationally lossless, I would argue. Saying that this is lossless after we have compressed it means nothing; the DV encoding still incurs losses, so it cannot be considered lossless.

[LocalH]

Well, I meant that in the sense of being able to move that DV stream anywhere you want without any further loss, hence "generationally lossless". You throw out a crapload of bits in the first place, but until you try to composite something on top of the DV video, you don't have to decode and reencode the video (which definitely does introduce generational loss). Whereas, if you move an analog signal around, even if it's YPbPr, you will lose some quality for each additional device the signal goes through (even though this loss is minimal depending on the analog format used). Technically, it's not the same type of 'lossless' as when comparing to true lossless video, where you get 100% of the exact same pixels as before compression (or with uncompressed video of course, since by definition uncompressed video is 100% of the original pixels). The way I see it, since people sometimes refer to "generation loss", then the lack of such loss is "generational losslessness". Nothing at all to do with the more common definition of losslessness.