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  1. Member
    Join Date: May 2011
    Location: Paris (France)
    Search Comp PM
    Hi,

    Here is the way i'm coping with vids :

    1. i download a video
    2. i recompress it with virtuadub, in order to add a logo, a signature or the name of a site with a very simple script :
    subtitle("tartanpion.com",191.324,size=23,text_col or=$765C3A).fadein(20).fadeout(15)
    3. i upload it and host it on a video platform YT ...

    It should be easy to obtain a very similar video (quality and size) but i didn't manage to do this.

    So my aim is to understand how to keep the same quality and how not to exceed the weight of the original video :

    In x264vfw, main codec options are :
    - rate control (crf or multipass)
    - presets (medium, faster, very fast)

    I've tried with different settings but to obtain similar quality, the result is 30% heavier than the original (crf 20, faster); as most of my videos are people talking in a studio (debates or interviews), i have chosen crf to obtain a good compromise quality/speed of encoding; (no die hard multi-explosions)

    When you download a vid, you often have choice between poor, medium and high quality; most of the time i choose medium because i don't really care about the level of visual quality : contents is more important for me (640x360 is enough good for me; this is called SD, isn't)

    I'm trying to establish a methodology for setting the best encoding parameters :
    1. i suppose i need to check some parameters from the original video throughout mediainfo
    2. then in video section, relevant parameters are:
    - Bit rate, Nominal bit rate, and Maximum bit rate
    - encoding settings : (cabac, ref, deblock, analyse, chroma,...)

    According to me, i should transpose something
    I'm lost; what should i put in x264vfw

    See attachment
    Attached Files
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  2. Member
    Join Date: Jun 2012
    Location: USA
    Search Comp PM
    There's really no problem here. If these are videos you or a client are producing, start with a much higher quality video in the first place and downsize it.

    If these are other people's videos that you are adding your name to -- that's basically illegal, especially in France which has pretty strong artist's rights protections.
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  3. file size = bitrate * running time

    If you want a smaller files use a lower bitrate. With CRF encoding you can't specify the file size.

    http://forum.videohelp.com/threads/362832-Can-the-output-file-size-in-Handbrake-s-Cons...73#post2305873
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  4. Member
    Join Date: Sep 2007
    Location: Canada
    Search Comp PM
    You will get slightly better results if you used better encoding settings. You're using 1 reference frame, subme 2 (these correspond to "--preset veryfast") only 3 b-frames . These are not very efficient encoding settings. For static content (like interviews), it also helps very much to have longer strings of consecutive b-frames

    I would use a slower preset (at least "medium") . Medium would correspond to --subme 7 - that's what the original used - it's a good compromise between speed and quality. I would also change something like --ref 4, --b-adapt 2, --bframes 8 (you can even go higher) . If navigation and seeking aren't an issue, you can even extend the GOP size by changing --keyint . All these suggestions increase encoding efficiency (better quality at a given filesize)

    Don't worry about maxrate(ie --vbv-maxrate and --vbv-bufsize), unless you have specific streaming or device requirements. Because the original used "CBR" (constant bitrate) encoding (this occurs when you use bitrate encoding mode and maxrate=bufsize). This will actually yield lower efficiency encoding, but perhaps "better" for some streaming situations . If you need to restrict the CRF encoding size, you can use these VBV parameters for "capping" the bandwidth, but it will reduce the potential quality. eg. --vbv-maxrate 800 --vbv-bufsize 800 . Using VBV constraints can only reduce quality, never improve. It should only be used if there are device restrictions or streaming restrictions - for youtube it doesn't matter because it's going to be re-encoded anyway
    Last edited by poisondeathray; 4th Mar 2014 at 10:09.
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  5. Member
    Join Date: May 2011
    Location: Paris (France)
    Search Comp PM
    Thanks for answering,

    @smrpix
    If these are other people's videos that you are adding your name to -- that's basically illegal, especially in France which has pretty strong artist's rights protections.
    I know this; fortunatly there are open source video that can be used by anyone; France is not famous for freedom of expression, that's why lot's of french upload their video on russian youtube (rutube) http://img15.hostingpics.net/pics/296663Capture.jpg


    @jagabo
    If you want a smaller files use a lower bitrate. With CRF encoding you can't specify the file size.
    Are you meaning that with a different process of rate control I could obtain keeping the same quality without exceeding the weight of the original video ?

    @poisondeathray,
    i will test compression with medium preset
    change something like --ref 4, --b-adapt 2, --bframes 8 --keyint
    Do you mean i can directly paste this on extra command line of x264vfw codec ?

    rc=cbr
    I did'nt notice this parameter before; i manage to generate through x264vfw : abr, 2pass and cqp. Not cbr
    Because the original used "CBR" (constant bitrate) encoding
    I've never seen CBR option in virtualdub except for audio compression; i guess constant bitrate encoding cannot be processed in vdub; what kind of video compression tool could have been used for original mp4 video ?
    this occurs when you use bitrate encoding mode and maxrate=bufsize
    Sorry, this doesn't clarify anything to me; again i ask if you're speaking of a process that can be done in vdub ?

    Sorry for my poor english; i hope this message make sense for you
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  6. Member
    Join Date: Sep 2007
    Location: Canada
    Search Comp PM
    The original video used x264, CBR encoding . You can does this with x264 or x264vfw. Just enter ABR bitrate, and set maxrate=bufsize. That is CBR encoding. I don't recommend CBR encoding. The average quality will be worse than if you used CRF or 2pass at a given bitrate

    Yes, you can paste on the extra commandline, or there is a x264vfw GUI that has the options as a checkbox (There are at least 2 different x264vfw versions)

    Just so you're clear - copying the original video settings doesn't mean you will get similar quality. You're re-encoding it so quality will always be worse if you use lossy settings . The original video's settings aren't optimal for compression . And then YT will re-encode it again, and the quality will suffer another round of generation loss
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  7. Member
    Join Date: May 2011
    Location: Paris (France)
    Search Comp PM
    So clear now.

    THX poisondeathray
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  8. Originally Posted by kaskaï View Post
    fortunatly there are open source video that can be used by anyone
    Am I the only one that sees a problem with this? Not that it's illegal but that it's unethical? And that it'll look like crap, however it's reencoded? And it'll be a very poor advertisement for whatever it is you're pushing?

    You download a poor quality YouTube (or some other) video. You reencode, this time adding your stupid logo and degrading it some more. You then reupload it to YouTube for YouTube to degrade yet again by reencoding. The result is a video 2 more generations removed from what was poor quality to begin with, and now with a logo no one wants to see. And it's in the public domain yet you mark it as yours by adding your nasty logo? But it's not yours. And as poor as the quality is by now, I wouldn't want my name or website associated with it at all. If you want your name on it, is there any reason not to add an annotation, instead of burning it into the video? It would save one step of quality-degrading reencoding.
    When you download a vid, you often have choice between poor, medium and high quality; most of the time i choose medium because i don't really care about the level of visual quality
    I guess you really don't care. Then why are you here asking for ideas how to make your videos look better? Isn't there a contradiction here? Always begin with the highest quality possible.
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  9. Member
    Join Date: May 2011
    Location: Paris (France)
    Search Comp PM
    Broadcasting 2 minutes of a commission of french senators preparing a dangerous law is useful for democracy : adding a logo is a detail; just consider the technical question and focus on this simple script : fadein(20).fadeout(15)

    You have no idea about collusion between French journalists and politicians ... ethic ? no : pathetic
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  10. Originally Posted by kaskaï View Post
    You have no idea about collusion between French journalists and politicians ... ethic ? no : pathetic
    About French politics? No, and I couldn't care less as politicians are the same the world over. About video encoding and public domain video? Yes, quite a lot, and my 'unethical' comment was all about that. Taking an open source video (and I'd have a hard time believing it's really open source if that source was originally from broadcast television) and 'branding' it as your own is what I think is unethical, especially if you've taken it from someone else's channel. Are you crediting that channel as the source of your video? No, I didn't think so. People do that all the time on YouTube (and to me quite often), take a public domain video, add their nasty logo, and then claim it as their own (complete with ads and trying to get rid of or claiming as their own other versions of that same public domain video).
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