Harddrive Camcorder

shredding · Post by **shredding** » Fri Jun 16, 2006 12:25 am

i understand the harddrive camcorder records in MPEG-2. this format is very bad for editing. Also the new HD camera records in MPEG-2. ARe there any software for good MPEG-2 editing?

Or does this mean it's better not to buy a harddrive camcorder? please shed some light on this issue.

jchunter · Post by **jchunter** » Fri Jun 16, 2006 12:37 am

Video Studio 10+ works fine for editing Mpeg2 in either standard definition or high definition. See Tutorial http://phpbb.ulead.com.tw/EN/viewtopic.php?t=13872

Your 1.8GHz CPU is marginal for high definition editing.
Video Studio 8 had/has a chronic audio/video synch problem - go for the upgrade.

shredding · Post by **shredding** » Fri Jun 16, 2006 1:07 am

thanks John.
I have a question, since MPEG-2 uses inter-frame compression. will that result in loss of picture quality when editing in Mpeg-2 format besides the audio/video synching problems?

jchunter · Post by **jchunter** » Fri Jun 16, 2006 1:32 am

I have edited and re-edited mpeg2 (recursively) video with ISO resolution charts imbedded. I can't see any loss of resolution or compression artifacts as long as the video bitrate is kept high (>=8Mbps).

However, transcoding from one compression algorithm to another MAY reduce picture quality because the information that is discarded by the first compression MIGHT be important for the second compression algorithm.

The best rule of thumb to preserve picture quality is to retain the original video encoding throughout the whole editing process - right through to the DVD burning stage (where Mpeg2 is mandatory). This means that the hard drive camcorder that you are contemplating should produce excellent DVDs because the original video encoding is DVD-compliant Mpeg2.

shredding · Post by **shredding** » Fri Jun 16, 2006 1:36 am

thanks John for your help. I'm considering buying a Harddrive camcorder in replacement of my old mini DV camcorder.

sjj1805 · Post by **sjj1805** » Fri Jun 16, 2006 4:07 am

Most users of this forum advise against editing MPEG2. There has only been one positive response to this thread.
If I was considering purchasing I think I would like to see more users opinions before investing in such a device.

shredding · Post by **shredding** » Fri Jun 16, 2006 4:12 am

Steve,
it seems like editing mpeg2 are never recommended. but it becomes unavoidable for HD cameras since they all record in mpeg-2. you think this is becoming the next standard? or someone has to develop some new method to store the HD avi?

or, does HD avi exist now? or is it just HD mpeg-2 format?

Thanks!

skier-hughes · Post by **skier-hughes** » Fri Jun 16, 2006 10:31 am

As Mpeg2 is a lossy formart each time you save it after making changes, so that the app used has to re-encode to make the changes there will be a loss of quality. Some apps can't just encode the changed bit and so encode teh whole movie which loses more quality along the whole movie.

HDV, which is an Mpeg2 format can be edited in a few ways, depending on which app you use.

Some will encode the movie as you capture to a i frame only type file, similar to dv-avi. This loses some quality, but not much. You can edit reasonably easily using this method. After editing it has to be encoded back to mpeg 2 and you then lose more quality.

It's hard to quantify the losses as much will depend on the encoder used to encode, the better this is the less the drop in quality.

The second method is to edit the mpeg file as it is. This means you can only cut at i frames. These are various distances apart depending on the encoder, but may be anywhere from 1/2 a second to a few seconds apart.
This means frame accurate cuts are not a possibility. Again, depending on the app used it will mean either just the edits or the whole movie will be re-encoded.

A freind of mine encodes his files to Mpeg4, this retains a fair bit of quality and enables frame accurate editing, similar to 1 above.

Bear in mind it is going to possibly be awkward to edit, it may be plain sailing as it is for lot's, but you only have to read the forums of all the apps to find for many it is fraught with problems as well.

If you want to do minimal editing, then I'd say yes, if you want to edit like you edit a dv-avi from your old minidv, I'd say think again at this stage.

Forgot to say, HD in a form similar to DV-AVI is available, but it'll cost you!!!!!! Sony do models at around £20,000 I think, may be more, it's been a few months since I saw them. HDV was invented to make use of minidv tapes recording, so they introduced the compressed HD format of HDV.

Graham

jchunter · Post by **jchunter** » Fri Jun 16, 2006 11:07 pm

Some of us, who have done extensive testing and editing with Mpeg2, have had excellent results with many hours of excellent quality video completed. I certainly would not hesitate to purchase a camcorder that encodes in mpeg2, if other features are suitable.

I highly recommend that members, who are continually denigrating mpeg compression, make a serious effort to try the mpeg workflow, measure the resolution and compression artifacts, and report any problems and successes - factually. Don't knock it if you haven't tried it.

Repeating hearsay and speculation is neither convincing nor scientific.

sjj1805 · Post by **sjj1805** » Fri Jun 16, 2006 11:37 pm

jchunter

Yes we know you're viewpoint, I have asked for others to put forward their opinions.

jchunter · Post by **jchunter** » Sat Jun 17, 2006 12:57 am

sjj1805,
We also know your opinions and are, respectfully, waiting for some facts to support them.

If you disagree with my work and my conclusions, please state your evidence (other than hearsay).

heinz-oz · Post by **heinz-oz** » Sat Jun 17, 2006 5:17 am

I don't disagree with your work (don't know any of it) or your conclusions. I know people who are happily creating VCD's and think the quality is great

For them it might be, for me it ain't, if you get my drift.

My results have prompted me to never capture to mpeg because of OOS errors and quality loss. I only do it to save time if I know I won't be editing the video, just preserving it on disc rather than tape.

I find your comment, that my response is based on hearsay, rather insulting. If I were to proclaim your opinion to everyone, that would be based on hearsay. I'm sure that there are many people who have made the same findings as I did, when they edited mpeg. There are plenty of posts on this forum to prove that.

If you are lucky enough to have it working for you, I congratulate you. Having said that, I will only recommend that workflow to someone when I have it seen working myself

I know that there are dedicated mpeg editing programs around which seem to work (never tried it because I don't need to) but to state that Ulead programs, this was a Ulead forum last time I checked, are capable of editing mpeg2 would be bullsh*tting a lot of folk. I for one will not do it just to please you.

sjj1805 · Post by **sjj1805** » Sat Jun 17, 2006 10:48 am

I do not intend to turn this post into an onscreen boxing match.
The point I made is valid without further need for explanation.

A forum member has come here asking for advice before making the final decision relating to spending hundreds of pounds of hard earned cash on a Camcorder and is hoping that the experience of our forum membership will help him decide.

This is good use of the forum and he is not whinnying moaning or knocking anything but simply asking a valid question.

I have noted that only 1 member of this forum had at the time replied and I am concerned that the poster of the question is not getting the feedback he deserves from our forum with the pro's and cons of the particular camcorder he has in mind.

This is not an excuse for a "mine is bigger than yours" type attitude.
There is still only 1 member who has provided positive feedback relating to this particular type of camcorder. I have not anywhere in this post told the original poster not to go out and purchase this item but simply drawn his attention to the fact that many forum members have expressed reservations about editing MPEG files.

This is not restricted to this forum. A simple Google search will provide masses of opinions.

http://tangentsoft.net/video/mpeg/edit.html wrote:Why MPEG Editing is Hard

Before you buy an MPEG editor, you must realize that MPEG was not designed to be edited. MPEG is a high-powered compression algorithm made for pre-edited video that is simply played back as-is and never changed.

The main thing that makes it difficult to edit MPEG video is that an MPEG encoder only puts out one full "reference" frame for every 14 or so "difference" frames. These difference frames only encode what changed since the reference frame. This is where MPEG's high compression comes from: difference frames are much smaller than reference frames. (This is an oversimplified explanation, but it suffices.)

Since difference frames depend on a previous reference frame in order to be decoded, the only place in an MPEG stream that you can do simple cuts is right before a reference frame. If you were to cut the video before a difference frame, that difference frame and all subsequent difference frames would refer to a preceding reference frame that doesn't exist any more. That stream would then fail to decode properly.

http://www.videoforums.co.uk/guide-videoredo-79.htm wrote:"Digital video is not film, you idiot!" This obvious (if pedantic) statement was recently made at videoforums, and conveniently sits as a fitting introduction to this particular guide: film can be spliced, moved and stuck together without requiring ten hours of re-encoding and at exactly the same quality. Do the same with an MPEG file and your stuck with re-encoding, losing your precious time and quality of the final video. Well the guys at VideoRedo are clearly an impatient, quality conscious lot and offer yet another way to bring the world of digital video closer to film.

http://www.manifest-tech.com/media_pc/hdv_jvc.htm wrote:Once you shoot your video in the cool new HDV format, there still is the issue of how to edit it. Not surprisingly, existing video editing software does not support interfacing to this new format. In addition, editing MPEG video is tricky, and therefore not well supported by most tools. Furthermore, the MPEG-TS (Transport Stream) format used for HDV is not commonly supported by desktop tools. For the moment, then, editing HDV requires new tools or new approaches.

The problem with editing MPEG video is that the MPEG format compresses runs of consecutive frames together as a group to take advantage of similarities between adjacent frames. You therefore cannot directly access arbitrary individual frames within the compressed data. Some tools provide limited support for MPEG by only permitting editing at group boundaries. More sophisticated MPEG tools support frame-accurate editing by doing a lot of work behind the scenes to provide access to individual frames by decoding the entire group around them, and then re-encoding the group together again. If not done carefully, this kind of churn from re-compressing blocks of video can quickly create visible compression artifacts

I could go one but as you say that would only be hearsay. So from my own experience I have found that editing MPEG files is fine most of the time provided you stick to simple straight cuts.
However the first time you insert a transition you have a very high probability of an out of synch audio/video issue.

I am glad to hear that this does not happen to you. Perhaps the rest of us are just unlucky.

I do not see any constructive purpose in answering any more of your comments in this thread which are clearly getting personal and so I shall not be doing so.

skier-hughes · Post by **skier-hughes** » Sat Jun 17, 2006 11:02 am

jchunter wrote: Repeating hearsay and speculation is neither convincing nor scientific.

The points I made were written after reading the links JC gave in another discussion on mpegs and the editing of. They are not hearsay or speculation, and as they came from the likes of cineform, I should think are scientific.

GuyL · Post by **GuyL** » Sat Jun 17, 2006 12:49 pm

jchunter wrote:Some of us, who have done extensive testing and editing with Mpeg2, have had excellent results with many hours of excellent quality video completed. I

I think the key here is "...some of us..." The fact is, most have experienced problems. IMO you have a better chance of experiencing problems than not.