a general question about video

[matriplex]

for a while I'm interested in videos and camcorders.but there are some problems for me.
firstly I want to start from camcorders.they encode video with its encoder(dv encoder, hdv encoder etc.) and after record it to tape.it means the quality is decreasing after it was encoded. after this we transfer the file from tape to pc without loss quality as DV-AVI HD-AVI
HDV-AVI etc. and we edit video cut video add something(fx ... etc) and we again encode it as DV-AVI HD-AVI HDV-AVI.it means again lose quality.

I want to ask that isn't there a problem?Am I wrong? are there any camera which don't encode video and record as uncompressed.avi. it's allright to encode one time. but camcoder and we encode so the video lose quality two times.

please help me.
I don't know english very very well so please use simple sentences.thx

[matriplex]

isn't there anyone who knows the answer?

[guns1inger]

Patience, grasshopper. This is a free service, with no obligation for anyone to answer. Wait at least 24 hours before bumping your own post. If you need to guarantee an answer faster than that, look up the yellow pages and pay someone for the service.

Someone like edDV or BJM can give you a more detailed answer, and I believe a similar question was answered within the last couple of days, if you search.

The short answer is

- No consumer cameras record uncompressed. The amount of data required to store the information makes this impractical. Even high-end DV camera formats are compressed

- Yes, there are generational losses, although depending on the software, these may be negligable if they are only one or two generations. Vegas and the Sony DV codec are very robust. I believe that the Canopus Codec is also very good.

- There is nothing to stop you doing all your intermediate work in uncompressed or losslessly compressed avi to stop you losing anything inbetween. The only inhibitor is space.

[matriplex]

thank you very very much guns1inger
but I want to ask a question more. what kind of camcorders do professionals(cinema film makers) use?
do they encode video two times as we?

[SaSi]

To my knowledge, DV Camcorders compress the video using DV codec, which is either totaly lossless or quality loss is negligible. Generation loss of quality is something that should not bother anyone really, unless you process the video repeatedly and do something to it.

If you just upload it to the PC and use any descent video editor to cut the video feed into pieces to paste together, then this should not generate any quality degradation. Applying filters to the pieces and also doing transitions is going to affect the quality, however I believe that the filter itself will modify the video much more than the codec itself.

HDV cameras are a different issue as they record the video using MPEG. This means that editing will cause some quality loss, however there are editors (like Mainconcepts EVE or TMPGENC Editor) that only re-encode the frames that are affected by cuts and transitions, so that both quality is maintained AND performance is much better.

[guns1inger]

Consumer DV compresses at a 5:1 ratio. Higher end DV formats compress at the same or slightly less, but there is still compression. Depending on the DV codec being used, and the filters and intermediate programs, generation loss can be apparent in as little as 2 - 3 generations, or as many as 5 - 6.

Most work for cinema is still shot on film, which is a totally different proposition to digital video. George Lucas and Robert Rodrigeuz have been espousing the benefits of digital video for highend cinema production, but it is still mostly an indi thing to help keep production costs down.

[edDV]

thank you very very much guns1inger
but I want to ask a question more. what kind of camcorders do professionals(cinema film makers) use?
do they encode video two times as we?

matriplex, I thought I answered that very question in this post a couple of days ago.

https://forum.videohelp.com/viewtopic.php?t=306299&highlight=

The makers of recording equipment work closely with their high end customers to determine recording needs. The tradeoff of compression vs. uncompressed is the number of minutes recorded on a given storage format (e.g mini DV tape could in theory record 12 minutes uncompressed or 60 minutes compressed) but it extends to all other equipment in the process.

Uncompressed video would force computers to use SDI interface and large RAID disk systems. These computers are available today in the $7,500 to $35,000 range but not everybody can afford that or only 12 minutes recorded per tape, so they choose instead DV format which can be edited on $500 computers.

Even Lucasfilm uses HDCAM-SR lossy recording equipment to make films like Star Wars 3 because uncompressed hard disk systems would be the size of a semi-truck at those resolutions.

I guess an analogy would be the supersonic Concorde vs. the slower Boeing 747. The airlines can make more customers happy with the slower jet. While all saw a benefit in flying supersonic, practical issues forced passenger airline speeds under Mach 1.

Those who have the need and money can use an uncompressed workflow today. This will become more affordable with each new technology generation.

It may be an elusive goal. Just when uncompressed standard definition became practical, the industry moved instead to higher definition using even higher compression than with SD. The demand for greater bit depth (e.g. 10, 12 or 14 bits) also forces higher compression.

do they encode video two times as we?

Yes, they do it for the same reasons. They record in the field or studio to a high end production format such as Digital Betacam, DVCpro-HD or HDCAM. They decompress that for editing and effects and then re-encode to several distribution formats.

HD bitrates start in the 100-880Mb/s range (compressed) in the studio. Later the final product is encoded down to 8-25Mb/s for HD broadcast or HD DVD.