1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Questions about the size of the vob after conversion

Discussion in 'MPEG-1 and MPEG-2 encoding (AVI to DVD)' started by Jinkazuya, Feb 4, 2007.

  1. Jinkazuya

    Jinkazuya Regular member

    Joined:
    Mar 26, 2006
    Messages:
    382
    Likes Received:
    0
    Trophy Points:
    26
    Well, this is what happens. When I try to convert the movies into DVD with my laptop, the size of the movies is less than that that convert with my desktop. For instance, the movie is 600 MB. After the conversion with my laptop, it is around like 4.0 GB. However, with desktop, the file is 6.0 GB. My question is how come? I just use the same software winavi to convert the movie but with different use of computer. But the result is vastly different.
     
  2. kitty66

    kitty66 Regular member

    Joined:
    Dec 18, 2006
    Messages:
    282
    Likes Received:
    0
    Trophy Points:
    26
    Double check the settings. It could be that you have one set to a different frame size. Or the quality settings are not the same. If they are then I have no clue, but I doubt this is true or you would be getting the same size output file.

    I could see different processing times. But not file sizes without variation in settings.
     
  3. Jinkazuya

    Jinkazuya Regular member

    Joined:
    Mar 26, 2006
    Messages:
    382
    Likes Received:
    0
    Trophy Points:
    26
    I will check it. But I think it is just the same. Is that the burner that affect the file size or the file itself?
     
  4. aldaco12

    aldaco12 Active member

    Joined:
    Nov 6, 2002
    Messages:
    2,544
    Likes Received:
    0
    Trophy Points:
    66
    The problem is that DivX (AVI) is more efficient than (MPEG-2) DVD.
    More, DVD movies are standard (720x480/576), AVI movies can have a minor resoution. For instance:
    640x360 (16:9)
    640x480 (4:3)
    Therefore, an 'acceptable' DivX (AVI) movie can have a bitrate ranging from 700 to 850 kbps. A DVD movie has a bitrate ranging from 2500 kbps and 8500 kbps. Its bitrate, is given by a bitrate calculator (for instance DVTool) which answers to the question:
    If I have a movie L minutes long contaning an (or more) audio stream(s) with A kbps, how large can be my V (video bitrate) to that authored (DVD movie) = 4.3 GB?
    For instance: a 120' movie with an AC3 audio very good (160 kbps) can have a video bitrate not larger than 4947 kbps.
    Remember: the size of the DivX movie has no meaning. It only depends on the length of the movie and the audio bitrate which the DVD will contain.
    Well, you can use the 'beauty' of the DivX movie to decide if the DVD movie can be encoded CBR (much faster) or VBR (slower).
    For instance, if you start from a 900 kbps DivX file, you'd better encode VBR, so you won't lose quality (for instance, the 4947 kbps movie will have a bitrate ranging from 2500 to 6500 kbps with averege = 4947 kbps; the encoding time will be longer because you encode multi-pass [1st - (N-1)th pass = analyzing; Nth pass = encoding] CBR is 1-pass (all segments will have a video bitrate = 4947 kbps).
    And if you start from a 500 kbps DivX file, encoding CBR won't cause a noticeable loss of quality.

    Remember: the DVD set length is given only by these stuffs:
    1) video MPEG-2 bitrate (the video encoder)
    2) audio bitrate (less influent)
    3) authoring (MPG --> VOB set + BUP + IFO) [more or less proportional to the MPG size]

    Understood?
     
    Last edited: Feb 4, 2007
  5. kitty66

    kitty66 Regular member

    Joined:
    Dec 18, 2006
    Messages:
    282
    Likes Received:
    0
    Trophy Points:
    26
    @aldaco12 - So as I understand your post then this is indeed a case of different settings?
     
  6. aldaco12

    aldaco12 Active member

    Joined:
    Nov 6, 2002
    Messages:
    2,544
    Likes Received:
    0
    Trophy Points:
    66
    Yes. I don't know how you 'convert', but all encoders have an option called ' video bitrate'. DVD movies range from 2500 to 9000 kbps, and can have up to N audio streams [having a bitrate which range from 128 kbps up to 448 kbps (5+1 AC3)] and N selectable subtitles.
    DVD encoder should know the allowed bitrate (which depends upon the movie length and the audio type(s)). I think you used the 'default' video bitrate value which, obviously, is too large for that movie.
    On old TMPGenc 2.5 the video bitrate was chosen automatically by the 'Project Wizard', once you give it the audio stream(s) number and bitrate.
    I don't know what your encoder does.
     
  7. Jinkazuya

    Jinkazuya Regular member

    Joined:
    Mar 26, 2006
    Messages:
    382
    Likes Received:
    0
    Trophy Points:
    26
    well, you seems to be knowledgeable, but I am such a novice that I don't quite understand. Thanks for the info though.

    Anyway, my question is whether the higher the bitrate, the better the quality of the movie or nicer the audio stream?

    Here is also my question. I convert all my RM videos with WINAVI. It is a convenient and fast way to convert your video. Just like one click, and the software will do everything for you. However, after the conversion, only if I convert the video into DVD format, I use Nero Vision 7 to join the all fragment things of the video just by clicking the botton of adding a new movie in DVD format. If I do that, I could store three videos into one 4.7GB DVD, which is in excellent quality. However, if I convert my RM video into MPEG-2 format, it converts faster than does DVD, when I open the Nero vision 7 and do the same thing, I am only able to store 2 videos, which provide me with very good quality. My question is I guess DVD and MPEG-2 seem to be the same. There is no much difference.


    Also there is video option at the bottom of the NERO VISION 7. And if you go to custom setting, there is a option of Bitrate. How can I adjust the bitrate? If I increase the bitrate, doesn't it mean that the video quality and audio stream would improve or get better?
     

Share This Page