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  1. #1
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    recompressing recorded video

    Hi

    I started this topic because I wanted to hear other people's opinion about recompressing videos that we have recorded with our camera/videocamera/DSLR. Usually the cameras produce huge files, and we loose quality by recompressing.
    I have a Nikon D3100 DSLR which records 1080p video into H264-Quicktime-MOV at 2.5MBytes/sec, and I check my videos on a Sony Vaio 17" laptop which has a 1080p display.
    Probably there were topics like this one before, but time to time a lot of people bump into this problem area.
    The point is I think a 1080p video should be enjoyable even 20 years from now, unless we screw it up with wrong compression or too low data rate, and one event or one vacation should fit on one DVD or less even in 1080p. Normally I dont keep filming for hours, just the important parts, on the last vacation I got 30 minutes total.
    The 1080p video coming out of my camera is so live like if I was there, while with Xvid 3Mbit-8Mbit recompression it seems to loose that feeling.

    First, recompress it at all, or leave the original format?

    What compression method or codec or setting to use?

    What datarate to use? For 1080p@24fps

  2. #2
    Be serious Franglais's Avatar
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    Re: recompressing recorded video

    Gee whiz. Nobody replied. Now I'm not an expert on the subject but...

    My video conversion software's default for producing 1080p Quicktime MOV videos is 10000K i.e. the output from the Nikon D3100 is compressed 4x more than my default setting. If I were you I would accept large files and not try to compress any more. Think about using Blu-ray disks rather than DVD. That's what they're for.

    You need to check what formats the graphics card on your VAIO can decode in hardware. If it's less than 2 years old then it can almost certainly do H264. It's not sure at all that it could do XVid, which is an older format. If it can't then your computer processor is having to do the decode, which is much slower and could explain the lack of fluidity. Check the cpu usage on your system when viewing a video in each format.

    BTW - are you sure you really need 1080p for your display? If you don't have a wall-sized screen then 720p may be enough.
    Charles

    Nikon D800, D7200, Sony RX100m3
    Not buying any more gear this year. I hope

  3. #3
    Moderator Skyman's Avatar
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    Re: recompressing recorded video

    Sorry I haven't replied I have been busy and it is hard to give the detail required on an iPhone. Basically compression only really happens twice with a dslr. Once when the video is created and once when it is rendered to a different file. Good non linear editing systems don't alter the file until it is time to output it. So really all
    You need to worry about is the compression you output it with. This is really determined by how you want to. Display the video. Is it DVD, blue ray, you tube / web or portable device (iPhone etc)

    Then all you do is pick the best format for those needs. Personally I like h.264 for most things. It is great highly compressed for iPhone and also uncompressed for blue ray. of course I'd you tube is your target then it is no good. If you think you might need a different quality at a later time but are unable to store the project indefinitely (with all the unedited files) then I suggest rendering a second archival copy at the highest quality your software and hardware will support.
    Quidquid latine dictum sit, altum videtur


  4. #4
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    Re: recompressing recorded video

    Thanks for the replies.

    "10000K i.e. the output from the Nikon D3100 is compressed 4x more than my default setting"
    -I thought that the D3100's video is h264 in 20000k data rate. If I make 8000k xvid then its 1/2.5 recompression.
    When I play the original H264 sometimes its not smooth, and seeking in the video file is very slow. In xvid its smooth enough. This might be a reason to still recompress it.
    I have a Vaio that I bought in november 2010 (VPCEC3C5E) and it has an ATI Radeon graphics processor on the motherboard and Intel Pentium dual core processor (introduced september 2010).
    I want to take videos in a quality that will still be acceptable several years from now. For example if I go on a once in a lifetime trip, then I might want to the check the videos i recorded 20 years from now.

  5. #5
    Be serious Franglais's Avatar
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    Re: recompressing recorded video

    2.5MByte per second = 2.5x8x1024 = 20000Kbits per second

    You're right the D3100 output is not compressed.

    If your PC is having problems reading and finding the file it may be that the disk is fragmented and it's taking time to read a large file. Have you got the disk defragmentation set up to run on the disk where you have your videos?
    Charles

    Nikon D800, D7200, Sony RX100m3
    Not buying any more gear this year. I hope

  6. #6
    Moderator Skyman's Avatar
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    Re: recompressing recorded video

    Remember that the whole file has to be loaded into ram and the player you are using should utilize your graphics card processor (gpu) try a different player especially if you are using windows media player. But no harm in compressing it for play back just keep the original file in case you want to edit it.
    Quidquid latine dictum sit, altum videtur


  7. #7
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    Re: recompressing recorded video

    its not the file size, i can open larger xvid videos (1-2GB) without problems.
    the camera output is compresset into mpeg4 with h264 codec by the camera.
    when playing it on the laptop the fan speeds up and very noisy, suggesting that its hard work for the processor to play it. when im playing xvid the fan is quiet.

  8. #8
    Moderator Skyman's Avatar
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    Re: recompressing recorded video

    Try updating the drivers and firmware for your gpu. It could be that it doesn't natively support h.264
    Quidquid latine dictum sit, altum videtur


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