Shrinking avi files

Discussion in 'Digital Video' started by conamor, Aug 10, 2017.

  1. conamor macrumors 6502

    conamor

    Joined:
    Jun 27, 2013
    #1
    Hi,

    I have some avi files that are around 400MB for a 3-4 minutes video file. Are there any way to reduce the amount of space that the file takes without losing quality? If so, what software is recommended to do that?

    Thank you
     
  2. kohlson macrumors 6502a

    Joined:
    Apr 23, 2010
    #2
    Reducing the file size will reduce the quality - just the way that works. So I think what you may be asking is: is there a way to shrink the file with minimal loss of quality. Handbrake, which can be adjusted to meet size and "quality" specifications. Free.
     
  3. conamor thread starter macrumors 6502

    conamor

    Joined:
    Jun 27, 2013
    #3
    Thanks! :)
     
  4. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #4
    400MB per 4 minutes is only 1.6 megabytes per sec. Just H264-encoded 1080p is about 4.5 megabytes/sec, and 4k from an iPhone is 5.7 megabytes/sec. So if you are ever going to record and deal with video, you'll have to accept this and get some hard drives.

    However your AVI files can likely be re-encoded to a more compressed codec while preserving almost all of the original quality. If done properly it's unlikely anyone would notice the difference.

    Unfortunately AVI is a container format not a codec. The material inside the AVI could be encoded with various codecs. The task is finding an app or utility that can (a) read that content and (b) transcode it at high quality to a more compressed format.

    There are many web sites advertising conversion tools, but you generally don't need those. As already mentioned Handbrake is free and works well. Since this is a Mac forum I assume you are on a Mac and have free access to iMovie. Unlike Handbrake, iMovie uses Quick Sync and can export to H264 faster.

    I just did transcoding tests of a 4.16 gigabyte, 18 min 16 sec AVI file from a Panasonic AG-DVX100 camera to H264 using both iMovie and Handbrake on my 2017 iMac 27. The default Handbrake x264 settings produced a 1.5 mbps file, and I used the iMovie export settings to pick the lowest bit rate of 2 mbps.

    There was minimal quality difference between the two transcoded files, and no difference between the Handbrake transcoded version vs the original AVI file.

    iMovie: 309MB, 1 min 30 sec
    Handbrake: 242MB, 2 min 44 sec

    Note that iMovie by default will use 720p and to retain the original 4:3 aspect ratio you must press "crop", then "fit" and the output will be pillarboxed 4:3 in a 720p frame. Handbrake by default makes a 4:3 output; how that is handled depends on the player.

    Despite the faster transcoding performance of iMovie, close inspection shows the Handbrake output is slightly sharper. Without further testing and experimentation I would probably use Handbrake.

    In comparing the original and transcoded output, another factor is NTSC AVI content is usually interlaced. When playing that back the deinterlace behavior depends on the playback tool. By default VLC does not deinterlace, although it has several deinterlace algorithms that can be enabled. It appears that both Handbrake and iMovie deinterlace by default when transcoding. They both produce a "hard deinterlaced" output file with the deinterlacing "baked in". So when comparing the original and transcoded material you'd have to use a player like VLC which can deinterlace the original to provide an equivalent image.
     
  5. conamor thread starter macrumors 6502

    conamor

    Joined:
    Jun 27, 2013
    #5
    This is great technical information. Digital videos isn't my cup of tea, I know the basics, I have strength elsewhere ;)

    I also have purchased FCP for editing, could FCP do something similar such as iMovie? What's funny is that 400MB video file (4 minutes) isn't that good quality because of the lightning. The file was burnt to a data DVD and I decided to throw away those DVD's, so I copied the file to the iMac. :)
     
  6. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #6
    Yes FCPX can do what iMovie can do but much more. However I had good results with Handbrake. If you have a ton of material to transcode it might be worth while experimenting with FCPX and evaluating what encoding parameters to use for the optimal combination of quality, file size and encoding speed, then compare that to Handbrake. This is because FCPX can probably encode faster due to Quick Sync. However if you just have a limited amount, or if it's a one-time job, then Handbrake may be easier.
     
  7. conamor thread starter macrumors 6502

    conamor

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    Jun 27, 2013
  8. Boyd01 macrumors 68040

    Boyd01

    Joined:
    Feb 21, 2012
    Location:
    New Jersey Pine Barrens
    #8
    I have been using Handbrake to process 720p30 ProRes422 video recently and very happy with the results. I have the current versions of FCPX and Compressor. Did not actually time it, but Handbrake seemed faster with SuperHQ 720p settings, the file was about half the size of the one I processed with Compressor and I couldn't tell any difference in the quality.

    I am using a 2012 quad core i7 2.6ghz Mini Server FWIW.
     
  9. conamor thread starter macrumors 6502

    conamor

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    Jun 27, 2013
  10. Boyd01 macrumors 68040

    Boyd01

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    Feb 21, 2012
    Location:
    New Jersey Pine Barrens
    #10
    Of course there is also Apple Compressor which is only $50 and can be used without Final Cut Pro. It's a very versatile program for things like deinterlacing, changing frame rate, size, speed, etc. Handbrake can do some of those same things, but each has its strengths. https://itunes.apple.com/us/app/compressor/id424390742?mt=12
     
  11. jweinraub macrumors 6502

    jweinraub

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    Jun 26, 2007
    Location:
    Sol III
    #11
    Just a curiosity question. If I film say a two or three minute clip, and it doesn't even need to be HD. I can use my old handicam, transfer it in FCP in NTSC resolution, and compress it and the clip will be HUGE. Granted, still significantly smaller than the raw footage, but when I get a 1080p video from the Apple trailers and save it, that file is tremendously smaller than my NTSC clip (yes I saved the file, not the buffering link). I own FCP X and Compressor, Premiere, etc and while I am an ameteur, I was never able to get it compressed to the levels I've seen on the interwebs. What am I doing wrong? I suspect the audio steam isn't compressing properly but haven't done enough experiments lately.

    I ask because I am still like to get back to copying all of my old VHS tapes and rather than store to dual layer DVDs, I rather just store as avi/mpg/&c. If you rather me open a new thread rather than hijack this one, let me know.
     
  12. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #12
    I can't download any Apple trailers to inspect the file characteristics, but if they are small it's because they were efficiently compressed and used a lower bit rate. There are many different encoding and compression parameters, not all of which are exposed with common tools. For a feature film web site they may have an encoding expert custom build a profile which is best matched for the material motion and image characteristics.

    You can inspect the encoding parameters using a tool like MediaInfo: https://mediaarea.net/en/MediaInfo/Download/Mac_OS

    Or Invisor: https://itunes.apple.com/us/app/invisor-media-file-inspector/id442947586?mt=12

    Whatever VHS capture software you are using gives certain encoding options. Those vary from one app to another. Some many give many options, others less. If not sufficient, you are better off capturing that in the lowest compression possible then transcoding and recompressing it to H264 using something like Handbrake or Compressor.

    Since you never know what each processing step is doing, each time you must examine the file characteristics with one of the above utilities. E.g, say the capture app has a slider which has "fast - medium - slow", or quality: "best - good - worst". What does that mean? Nobody knows.

    In general if your attempts to date have not produced a small enough file, it's because some link in the chain is using a higher than needed bit rate or less effective compression settings.

    Before you commit to a lot of capturing/encoding, always test one small piece then closely examine the results with various players, including VLC and Quicktime. You don't want to do a lot of work and find (for example) something messed up the deinterlacing.
     
  13. Boyd01 macrumors 68040

    Boyd01

    Joined:
    Feb 21, 2012
    Location:
    New Jersey Pine Barrens
    #13
    Really don't understand what you're talking about here, things like "huge" are subjective, can you give us an actual example of file sizes? I'm working quite a bit with legacy DV footage at the moment. An hour of DV is about 12gb. Just finished one project from 4:3 DV footage shot on my Sony VX-2000 in 2002. I added a lot of effects, color correction and titles so I exported it as uncompressed deinterlaced SD which of course created a huge file. I then processed it with Handbrake using the high quality settings which resulted in a 2gb file for an hour. So that is 1/6 the size of the original.

    I'm sure I could have compressed it into a 1gb file that would satisfy most people (1/12 of the original size). Have ripped over 1000 standard definition DVD's using Handbrake and they're mostly between 1gb to 2gb for movies that are typically 2 hours long. I also have the current versions of FCPX and Compressor and they are great programs. But for creating the smallest high quality files I'm having better luck with Handbrake. For another short project Handbrake made a file half the size of Compressor, took about the same time (maybe less) and I couldn't tell any difference in quality. I used the Handbrake SuperHQ 720p30 setting for that one.

    Are your VHS tapes personal video of family, etc. or commercial videotapes? Are they S-VHS or regular? Were they recorded in SP mode? I have a lot of old VHS tapes too and awhile ago I dragged an old VCR out of the attic and tried to watch a few. After about 15 minutes it all went back to the attic. VHS quality is unacceptably poor in today's world, IIRC it only has about 300 lines of resolution. S-VHS is a bit better but never really caught on. And if the tapes weren't recorded in SP mode, they are really terrible. Of course, if they are valuable personal family videos that's another matter. But otherwise I don't think it's worth the effort of digitizing.
     
  14. maulll macrumors newbie

    maulll

    Joined:
    Aug 10, 2017
    #14
    I always use my video converter to shrink large files. It's named as WinX HD Video Converter Deluxe, but it also serves as video compression software because it can adjust video audio parameters.
     

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