Avid 2:1 vs Digibeta 2:1

[Job Ter burg]

DigiBeta is slightly more compressed than 2:1.
What happens is that the 2:1 footage is played back (decompressed) over SDI into the DigiBeta deck, which in turn compresses it with its own proprietary codec. So yes, compared to the original, compression is applied twice.

[Daniel Edelman]

Thanks for the info. This questions spurred from a discussion about how to decide proper capture settings based on final output. I usually make the decision based on bitrate. Eg: We upres to DNxHD 145 because we output to HDCAM, which is 144 Mb/s. Is using the bitrate a good way to decide which codecs to use?

The Goods: Avid MC 2.2.15 Adrenaline, Symphony Nitris 1.6.5, Unity 3.5. HP xw8200 turn-key computers. AJ-HD1400, 1200, HDW-1800, HDW-F500, DVW-A500

[Bouke Vahl]

Bitrate and quality have a very strange relation.
The noisier the original, the higher the bitrate must go to have good results.
Next there are the different codecs. MpegII based codecs give great results on very low datarates, and the I frame only variants are easy to work with.
There is (a bit) of consensus that recompression to the same or alike codec yields the best results. But that is theoretical.
If you can, (that is, probably not with HDV or H264 material), use the native codec as long as you can. It is fast (no recompression) and storage efficient.
For going from digibeta to HD-cam, i would think that the scaling applied is more important than the datarate. Do test a lot of options, and let your eyes decide.

Bouke

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[Daniel Edelman]

Thanks for the insight.
At my job i’m regularly presented with a myriad of tapes which need to make it into Avid. It’s usually on a large scale, so there is no room for error (like digitizing 50 tapes at a sub-par resolution).My main goal here is create a rule of thumb that will help me decided what’s the best resolution to use depending on the source and final master tapes. I know it’s not so cut and dry, but any guidance is greatly appreciated.

The Goods: Avid MC 2.2.15 Adrenaline, Symphony Nitris 1.6.5, Unity 3.5. HP xw8200 turn-key computers. AJ-HD1400, 1200, HDW-1800, HDW-F500, DVW-A500