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  1. Member
    Join Date: Aug 2007
    Location: Norway
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    I have downloaded MPEG-1 video clip 37 GB bitrate 1.15, width/height 320/240, framerate 29.970. Using Roxio Easy Media Creator I want to trim the clip maintaining highest quality in output file. Using MPEG-2 for output file, despite increase to 248 GB, bitrate 9, width/height 720/576, framerate 25.000 the loss of quality in output file is unacceptable. Is a loss of quality inevitable if you want to cut the first minute of a video clip or is there a way around this?
    Thank you
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  2. Use an MPEG editor that doesn't reencode except where necessary. Like Womble MPEG Video Wizard. This won't work if you're making a DVD though -- DVD doesn't support 320x240.
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  3. The cut is not the problem, many softwares will handle that with no loss. Your problem is that you are resizing way upward, changing framerate, and then re-encoding. I would avoid those steps if at all possible.
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  4. Always Watching guns1inger's Avatar
    Join Date: Apr 2004
    Location: Miskatonic U
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    You are blowing up your video by a factor of four, which is a large increase that will result in blurring and enhancing any existing defects.

    You are working from a low quality, high compressed source.

    You are re-encoding from a lossy codec to a lossy codec. Mpeg (1/2/4) simply does not like being encoded multiple times.

    You are reducing the framerate from 29.970 to 25 fps. This will be done, depending on the encoder, but either throwing away 1 frame in 5, causing jerkiness, or by blending frames, causing blurring and motion artifacts.

    As pointed out by Nelson37, if you avoid the enlarging and change to framerate, you will avoid a lot of the damage. You can author DVD using VCD resolution and mpeg-1, and most PAL equipment will playback NTSC footage.

    If you must re-encode it, say, as an intellectual exercise, then use virtualdubmpeg2 to do your editing, and use some of the MSU filters, such as Smart Deblocking, to try to minimise the damage. You will still end up with softer footage, but it might be more acceptable to you.

    But bottom line is that you have have a low resolution, low quality source, and there is very little to you can do to change that other than incrementally.
    Read my blog here.
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  5. Member
    Join Date: Aug 2007
    Location: Norway
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    Thank you all!
    Your answers have taken my understanding a big leap forward.
    No - I do not want or need to make all these changes in bitrate, file size or codec. I only want to do the cut and leave everything else unaltered. But this is the only way Roxio EMC knows how, and Roxio EMC is the only tool I know. And I want to burn the resulting video to DVD. Actually spesifications of the original video clip are good enough, they look great on the TV.
    Are videoredo or http://www.videohelp.com/tools/sections/video-editors-mpg-dvd tools that will cut only and let the result burn to DVD?
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  6. Try Mpg2Cut2. It's one of the few free MPEG cutters that doesn't require demuxing the audio and video. I believe it does limit you to cutting on keyframes though. MPEG typically has a keyframe about every 1/3 to 1/2 second.
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  7. Member
    Join Date: Aug 2007
    Location: Norway
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    Thank you jagabo, I`ll try that. Makes me wonder though why Roxio does not give me this option. Editing video increase file size to such a degree that a 300 GB external HDD is soon filled up. Does Nero give you this option?
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  8. Always Watching guns1inger's Avatar
    Join Date: Apr 2004
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    Originally Posted by karebo
    Makes me wonder though why Roxio does not give me this option.
    Because Roxio, and Nero, are basically consumer toys. Yes, they make it simple for beginners, but they do this by reducing features, hiding the true complexity of the task, and foregoing the niceties, such as quality.
    Read my blog here.
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  9. Member
    Join Date: Aug 2007
    Location: Norway
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    Thank you guns1inger.
    Now, maybe the core of the issue is what you stated in your first reply:
    You are re-encoding from a lossy codec to a lossy codec. Mpeg (1/2/4) simply does not like being encoded multiple times.
    I actually did try to output the trimmed video in MPEG-1, trying to alter output spesifications as little as possible but the picture quality was disasterous. Since MPEG 1/2/4 does not like being re-encoded and since the source video is of low quality -maybe the loss of quality wuld be unacceptable whichever tool I use, be it MPG2cut2, MPEGStreamclip or whatever?
    Would it give a better result if I first converted the video to another codec (if so, which would you recommend?) and then did the cutting in the converted file?
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  10. maybe the loss of quality wuld be unacceptable whichever tool I use, be it MPG2cut2, MPEGStreamclip or whatever?
    There is no loss of quality when using a cutting tool that doesn't reencode. You'll get the same lousy quality you started with (if it's MPEG-1)
    Would it give a better result if I first converted the video to another codec...
    No.
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  11. Member
    Join Date: Aug 2007
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    Thank you manano
    I understand that I have to install a tool to do the cutting then. To a novice in this field the tools section in video editing is a bit overwhelming. Jagabo already suggested I use Mpg2cut2, but what about MPEGStreamclip? Or any of the several others? I would appreciate suggestions from experienced videoeditors on which to download for this specific purpose. By the way I do have other editing tasks too, ie 1,5 GB size WMV in one chunk that IŽd like to cut into chapters.
    But primarily: an easily operated tool to cut downloaded MPEG-1 videos
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  12. FYI:

    MPEG encoding breaks the video down into small Groups of Pictures. Typically 12 to 15 frames.

    The first frame of a GOP is saved like a JPEG picture -- the entire frame can be recontructed from this information. This is called a keyframe. The rest of the frames in the GOP only encode the changes from frame to frame. This is one of MPEG's main space saving techniques.

    A dumb editor will let you cut an MPEG anywhere you want but will uncompress all MPEG frames and reencode them again. This will degrade the picture quality and take a long time.

    A GOP level editor will only let you cut at keyframes. This type of editor is very fast and there is no loss of quality because nothing is reencoded. But the granularity of edits is about 1/2 second as there is only a keyframe about every 1/2 second.

    A smart MPEG editor will allow you cut anywhere you want and will reencode only the GOPs that need it -- only the cut GOPs are reencoded. This type of editor is fast and you only lose quality at cut GOPs.

    If you want to perform any kind of filtering (like noise reduction, color changes, etc.) every frame has to be decompressed, filtered, then recompressed. Many programs are built around this decompress-filter-recompress model and perform the decompress and recompress steps even if no filtering is performed.
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  13. Member
    Join Date: Aug 2007
    Location: Norway
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    Hello again (one week vacation)
    Thanks again for your excellent advice and efforts to educate me which I appreciate very much.
    I downloaded MpegStreamclip, principally because it promised to edit MPEG-1 and seemed easy to download.
    Experiencemy videos are typically 10 min, cut in 4 pieces, each with an initial commercial attachment that I want to remove to create a continuous video, which means that initial and concluding keyframe should be included in the cut?)
    1. Played on Quick Time all cuts and joins were excellent. On WMPlayer and Roxio DVD burner several of the transitions halted, the concluding picture continuing for several minutes.
    2. After having used the program for several days, reading the user guide included in the download in Word format, I was informed by the system that "Word has a problem and has to be stopped". Then a total system crash. Unable to boot Windows XP. Luckily I have an Acronis True Image backup.

    My plan now is to find a DVD burn tool that will burn the MpegStreamclip videos (MPEG-1 Quick Time). Any suggestions for a good tool? Or a better plan?
    Was the system crash caused by the MpegStreamclip download? Dare I download it again?
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  14. Member
    Join Date: Aug 2007
    Location: Norway
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    Success!
    I went for a "better plan" after a more thorough study of relevant guides on this site and tried Movica. This tool splits and joins the videoclips to a format that readily burns on Roxio Easy Media Creator.
    Thank you all
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