As mentioned in my firts thread, "Preparing for Cinelerra on openSUSE 10.2", I'm sitting on a lot of analog Hi8 PAL tapes (S-video) containing my recordings during 15 years. These analog sources have to be converted to high quality digital video for backup purposes and later editing.
At first, A/DV converting might look to be straight forward. But exploring the subject a little more, I think there are more to consider to find the optimum options or solution. As a background to explain why, I've extracted a couple of sections from Adobe's white paper, "DV Compression Primer": page 11 Analog-to-DV converters ----------------------- Certain devices can perform a live conversion from analog video formats to DV25 for capture. They usually offer composite, S-Video, and unbalanced analog audio conversion to the DV format for storage on the computer. The 25-Mbps data rate of DV is sufficient for content that camcorders produce, but it can be troublesome for converting sources with significant analog noise on lower-end versions of the converters. page 13 Choosing the right capture codec --------------------------------- When you capture content, you must choose an appropriate codec. The choice depends on the capture hardware you’re using, the format from which you’re capturing, and your storage requirements. There are three basic types of codecs to choose from: DV, Motion JPEG, and uncompressed. DV codecs The DV25 format is ideal when capturing from a DV25 deck. Over a FireWire connector, you can use DV25 to copy the native bits from the tape onto a hard disk, making a perfect copy. If you use a different format at a higher data rate, the resulting video will be slightly lossy. Using a DV bridge to convert analog source to DV25 may work, but the quality lessens. The data rate of DV25 isn’t quite enough for optimal encoding from source with analog noise. Also, the 4:1:1 color space also entails a loss in quality. Motion JPEG codecs Motion JPEG has been the leading format for high-end video-editing systems for some time. The proprietary codecs supported by many vendors of capture cards, for example the Targa and Pinnacle codecs, are variants of Motion JPEG and share its properties. Motion JPEG is 4:2:2, and most implementations allow you to specify a data rate or quality level. Some implementations can even create a mathematically lossless Motion JPEG. Typically, data rates of 50 Mbps or greater are considered broadcast quality. http://www.adobe.com/motion/primers.html ----------------------------------------- Reading the above, I wonder if converting using the DV25 codec neccessary is the best format to preserve the original S-video quality for NLE and backup purpose. Looks like both colors and video quality from low light situations (noise) may suffer. NTSC DV 4:1:1 color sampling is mentioned, 4:2:2 for MJPEG and 4:2:0 for PAL DV, and 4:2:0 also for DVD and HDV using MPEG-2 compression. The typical DVD delievering format has previous been considered not to be of interest in this context, because it is so much compressed that it is expected unuseabel for later editing purposes. But now also HDV use MPEG-2 and this format has also become possible to edit directly on powerful hardware. Especially if there arise BD or HD-DVD burners that can import and convert analog video to a less compressed digital format, they will be of interest also as a editing format beside as a backup medium already. That is, is a typical A/DV convertor like Canopus ADVC 110 or Datavideo DAC-200 using DV25 codec the only practical and best solution to preserve initial S-video quality as converted to digital video? So far I haven't seen it will be possible to preserve the Hi8 RCTC time code, which also includes time and date of the recordings. http://www.sirentechnology.co.uk/pages/products/categories/enc_conv/conv.htm Well, from before I already have a useable Videonics MX-1 videomixer with a built-in TBC. MX-1 has S-video IN/OUT and does internal apply a digital conversion 13.5 MHz, 4:2:2 8 bit and resolution 5,0 MHz. Beside I have a Videotech VCC3010 video corrector with individual RGB color correction controls (white balance). I plan to use these devices on the analog stream before the A/DV converter, and therefore don't need these features in a more costly A/DV convertors. Although color corrections also can be done afterwards with Cinelerra, I think it will best to clean up colors and TBC directly on the analog side before digitizing. Right? To sum up: 1. Which options are available for capturing S-video to Linux, thinking NLE next with Cinelerra? 2. Which option/solution preserves the optimum initial Analog video quality? 3. Which backup options are available to preserve the source in editable quality on digital media? Terje J. Hanssen _______________________________________________ Cinelerra mailing list [email protected] https://init.linpro.no/mailman/skolelinux.no/listinfo/cinelerra
