confused by different video formats

Discussion in 'Amateur Video Production' started by Brian, Mar 8, 2014.

  1. Brian

    Brian Guest

    I was using the program MediaInfo to look at the properties of a video file
    that I had downloaded from the internet.

    It says the following:
    General Format: AVI
    Video Format: MPEG-4
    Format settings, Matrix: default (H.264)
    Codec ID XviD

    The file extension is AVI.

    So there seems to be a mixture of video formats. All I want to know is what
    video format the file was compiled in?
    In other words if I was was going to compile the file from a video editor
    or video converter then what file format would I choose that matches the
    video format of this file?
    Brian, Mar 8, 2014
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  2. Brian

    HerHusband Guest

    It sounds like an Xvid video. Xvid is an open source competitor to the
    commercial Divx video encoder:
    xvid and divx are what I consider "old technology". I used them years ago,
    but these days I prefer regular h.264 MP4 files. Equal or better
    compression/quality and much better compatibility with media players.

    I still run across the occasional xvid or divx file, but convert them to
    MP4 if they're something I want to keep.

    Anthony Watson
    HerHusband, Mar 8, 2014
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  3. Brian

    Gavino Guest

    I hope you mean that you simply remux them from an avi container to an mp4 container.
    Not 'converting' the contents (to H.264, for example), which would degrade the quality.
    Gavino, Mar 8, 2014
  4. Brian

    Brian Guest

    My aim is to create a small file with high quality.

    So I started to look at files done by other people that I've downloaded.
    Some manage to have a 50min to 1 hour recording in a 500 MB file that is of
    good quality on playback.

    I have a 50 minute recording as an example of an old TV series in 4:3
    format that I recorded using the hardware Dazzler (analog to digital for
    video and audio into usb port of the computer).
    It created a 1.8 GB mpg file at a video sampling rate of 4Mbit/s 720 x 576.
    It was recorded in 720 x 576 by the TV station so 16:9 video ratio adverts
    could be added. There are black bars each side of the picture to show a 4:3

    Trying to convert it to mp4 at a video bitrate of 4000 gave me a file size
    of 1.16 GB. (720 x 400)
    Converting it to mpg VBR video bitrate average 3000 peak 4000 kbit/s gave
    me a file size of 1.27 GB. (720 x 400)
    Converting it to DivX with a 2Mbit/s video rate (720 x 400) gave me a file
    size of 669 Mb (the smallest so far).

    I know you don't like DivX but it does give me a smaller file size than MP4
    at the same video quality.
    Brian, Mar 9, 2014
  5. Brian

    Paul Guest

    Just for future reference, movies consist of a "container format",
    which can use multiple different CODECs inside.

    "AVI, Matroska, Quicktime Mov are containers"

    Inside the container, the video track is encoded with a CODEC.

    I still don't understand the terminology MediaInfo used
    in its output. An alternate to MediaInfo (rather old now),
    is GSpot.


    For highly compressed formats, the compression is lossy,
    and changing the file from one type to another, can
    impose another generation of detail loss. So archiving
    the original video is one issue. Generating useful
    formats for distribution or viewing is a separate
    consideration. You would keep the original file around,
    if the re-encoded ones looked bad.

    Paul, Mar 9, 2014
  6. Brian

    Brian Guest

    Thanks Paul for the internet links.
    I don't see MKV in the video lists but maybe it was not around when the
    lists were made.
    Far as I know MKV is a container and it seems to add chapters to the video.
    MKV must be popular as I've seen programs that convert video from DVD and
    video file to MKV only.
    Brian, Mar 9, 2014
  7. Brian

    HerHusband Guest

    If the divx/xvid is important to me, and the format is compatible, I try to
    transcode to MP4 or MKV to retain the original quality.

    However, most of the stuff I find online isn't that important to me anyway.
    I'm usually clipping out something that interested me, or downsizing it so
    I can play it on my iPad or Kindle fire. In these situations file size is
    more important to me than quality loss. I often take a multigigabyte 1080p
    or 720p original, clip out a portion I am interested in, and reencode to a
    smaller MP4 (such as 800x450) at a lower bitrate. The result is usually
    just 100MB-200MB. Of course, I would never do this with something that was
    valuable to me.

    Other times I reencode at the same size/bitrate because the original
    encoding is messed up. Transcoding just transfers the odd encoding into the
    new container. I'm willing to trade a minor quality loss for improved
    playback and compatibility.

    Anthony Watson
    HerHusband, Mar 9, 2014
  8. Brian

    HerHusband Guest

    To some degree, file size and quality are mutually exclusive. :)
    Bitrate is the biggest determining factor in file size, followed by the

    If you encode to (h.264) MP4 at 2Mbit/s with the same 720x400 resolution,
    I'm betting it will come out very close to the file size of DivX.

    Decrease the bitrate and the file size will get smaller. You can also try
    decreasing the audio bitrate, though it won't have as much impact.

    The advantage of MP4 compared to MPEG2 is that it retains more quality at
    lower bitrates. You might be able to go as low as 800Kbps-1000Kbps with
    MP4 and get good results, whereas MPEG2 would generally look bad at that

    You should also find a converter that will let you trim the black bars so
    your video is the original 4:3 aspect ratio. No reason to waste bits
    encoding black bars.

    Of course, if this video is important to you, you should keep the
    original 1.8GB MPG file.

    Anthony Watson
    HerHusband, Mar 9, 2014
  9. Brian

    HerHusband Guest

    MKV is the "Matroska" format. It is listed on the page Paul supplied.
    MKV, like many container formats, "support" chapters but do not "require"
    chapters. I have many music videos in MKV format that do not have chapters.

    From what I've heard, MKV has slightly less "overhead" than formats like
    AVI do, and it supports a wider range of video codecs.

    If you're concerned about compatibility, keep in mind HTML5 and BluRay
    discs both support MP4, but neither support MKV...

    Anthony Watson
    HerHusband, Mar 9, 2014
  10. Brian

    Gavino Guest

    Maybe we have a difference in terminology.
    I would call transferring the old encoding into a new container (without re-encoding)

    To me, 'transcoding' suggests converting the old encoding to a new encoding, eg Xvid->H.264
    (whether using the same container format or not).
    Gavino, Mar 9, 2014
  11. Brian

    HerHusband Guest

    Hmm.. Looks like you're right. I've always thought of "transcoding" as
    losslessly converting a video to a new container. After a little research,
    "Remuxing" does seem to be the correct term.

    In any case, we have the same idea, I was just using the wrong terminology.

    Live and learn... :)

    Anthony Watson
    HerHusband, Mar 9, 2014
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