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  1. Member
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    hi there, taking a 1080/50p m2ts file and outputting it to 720/50p m2ts or mp4, is it better to do the encode with 2 passes, or is one pass ok.

    just reading conflicting stories about this, just like reading different opinions about whether you should do a single or double pass encode when converting HD video (h264) to Mpeg2 (dvd) format, in which this case i always do a 2 pass encode anyway.

    cheers
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  2. There is no such thing as 1 pass (CBR, CRF, CQ) or 2pass (VBR) is better or worse , encoder always does its best ,

    1. The question is I have video of THIS length and I want to squeeze it to THAT size. Using 2pass VBR.

    2. Or I have video that I care to compress and I want THIS quality, using 1pass CRF.

    It is up to you what approach you choose. #2 is flexible though, you can try to encode just 10 seconds and you know what quality it is giving out and then you change CRF accordingly . After that you are set for many, many projects of yours. As for 2 pass VBR, you have to encode it all, and then you go scene after scene to check what you got. But as I said in case of restricted space this is what you have to do to be most effective. And you never know what you are going to get, using 2pass VBR.

    Do not use 1 pass VBR. 1pass CBR also , not much effective, , except DVD in this case, if you know that DVD is not longer than say hour and 10 minutes, you can use it, waste of space , sure, but who cares how full the DVD is.
    Some encode AVCHD 28 Mbps or so (not sure about exact bitrate) , there is different bitrates available I guess, that is 1pass CBR, well, whatever works, ...
    Last edited by _Al_; 9th Apr 2014 at 17:52.
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    hi, im not trying to convert to any set size, i use VRD and it has built in quality presets that we can use, or we can modify those presets to suit our own needs, and it uses variable bitrates.

    the built in preset will output a 1080/50p m2ts to 720/50p m2ts @ 12Mbps and if i convert that to 720/25p (half the framerate) the output file is around 6Mbps, but i have always been using 1 pass, and have been told by the devs over at VRD to use 2 passes, and it gets very confusing.

    just as some people (including the Devs at VRD) tell me to convert 1080/50p m2ts files to Mpeg2 as progressive (their h264 to Mpeg2 preset does this automatically) there are others who say to encode them as interlaced.
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  4. Originally Posted by glenpinn View Post
    just as some people (including the Devs at VRD) tell me to convert 1080/50p m2ts files to Mpeg2 as progressive (their h264 to Mpeg2 preset does this automatically) there are others who say to encode them as interlaced.
    It depends on the source whether you keep it interlaced or make it progressive. By MPEG-2 do you mean DVD? If so, progressive sources can be encoded for PAL DVD as either interlaced or progressive. Retail PAL DVDs of progressive sources (like movies) are usually encoded as interlaced. Of course, interlaced sources should always be encoded as interlaced. Do you notice there's a difference between what the source or content is like and how it's encoded? You may not be understanding what you're being told and are garbling it in the 'translation'.
    ...im not trying to convert to any set size
    Then you should use 1-pass CRF. Not 1-pass ABR or CBR. Get the quality you want and forget about the size.
    Originally Posted by _Al_ View Post
    Making 25p you loose temporal resolution.
    If the source is a progressive movie then every other frame is a duplicate and you lose nothing by making it 25fps. Or are these home movies? A sample might help.
    Last edited by manono; 9th Apr 2014 at 19:06.
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  5. Originally Posted by manono View Post
    If the source is a progressive movie then every other frame is a duplicate and you lose nothing by making it 25fps. Or are these home movies? A sample might help.
    There was mentioning 50p at the beginning of this thread, if it was about movies I would perhaps not responded at all, I thing it is 50p camcorder footage.
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  6. My mistake then. I apologize, and thanks.
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    VRD uses Variable bitrates for all its outputs, and if i ever convert my 1080/50p h264 files to 1080/25p, or 720/50p or 720/25p h264 then i always use their built in "Quality" mode preset (as you can see in the screenshots below)

    this is my 1080/50p m2ts to 720/50p m2ts profile, and my 24Mbps 1080/50p m2ts source file will output to 720/50p m2ts @ around 11Mbps
    http://www.mediafire.com/view/p2ip8z5rm8d9oel/VRD_720-50p_m2ts_profile.jpg

    this is my 1080/50p to 720/25p m2ts output profile, and because the framerate goes from 50p to 25p the output 720/25p m2ts file will be around 5.5Mbps
    http://www.mediafire.com/view/lod38b47obm4vn6/VRD_720-25p_m2ts_profile.jpg

    if i convert from 1080/50p to Pal dvd Mpeg2 then i use this profile, except i use the "Bitrate" mode set to 8000kb, and Mpeg2 outputs also uses a variable bitrate, not constant.
    http://www.mediafire.com/view/e46k8sny38370sb/VRD_720x576_mpeg2_profile.jpg
    Last edited by glenpinn; 9th Apr 2014 at 19:58.
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  8. If that 1pass is VBR, it is good to recommend not to use it.
    But if that 1pass is CRF , then why not, you can use it, I'd even prefer it.
    Or is it CBR? Those values 12Mbit or 6Mbit are average or just constant bitrate?

    To encode DVD from HD,50p, was discussed here too. Making 25p you loose temporal resolution. Strobing is going to be present.
    Is that software simply dropping every other frame? Then your result very is sharp but with some strobing in motion)
    Some videoeditors use blending making 25p to complicate things. Not sure what your software does.

    That is why to better use 25i, to keep that temporal resolution but, big BUT, low pass filter, or vertical blur should be used (or other method I do not know about) to not have interlace lines flickering. This vertical blur will get result not so 100 % sharp as 25p sharp resize but motion is fluid (as was recorded).

    So it depends what your software actually does with that footage, maybe that is why they recommend mpeg2 as progressive 25p knowing that is best compromise for their software. The longer shutter you shoot with, the better result with 25p, but anyway, never that smooth as original.
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    ok, this is 1080/50p avchd video from my camera, sorry if it was confusing.

    VRD converts h264 to h264 using variable bitrate, and the Devs told me to do a 2 pass when re-converting these 1080/50p files to say 720/50p or 720/25p h265 (m2ts or mp4)

    if i convert the 1080/50p file to a Pal dvd compliant Mpeg2 file i use VRD uses variable bitrate, and i have been advised by the Devs at VRD to do a 2 pass on this as well.

    i will upload some sample 1080/50p m2ts from mt camera as well as my 720/50p m2ts and 720/25p conversions using single and double pass so you can download them and see for yourself.
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  10. As for mp4 content,
    You want to know why 2pass or 1pass but you do not say what kind of 1pass you have available, CBR, VBR or CRF.
    1pass CBR is not economic at all and high bitrates are being cut off. If bitrate is high enough - some use this method for whatever reasons - 1pass only, or simply software does not have CRF or they just do not care, thinking AVCHD (1pass CBR) is more compatible, etc..
    1pass VBR is trying to stick close to bitrate value, but it is not economic also.
    1 pass CRF must have that CRF value selected, not bitrate, not sure if VRD can do it as well. 1pass VBR is not 1 pass CRF.

    DVD approach I explained too. I doubt that there is any vertical blur involved in making 25i DVD from 50p HD original. So that is why they recommend 25p out 50p original perhaps.
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  11. Looking at those pictures, I do not know what that "Quality Mode" in videoredo does exactly. They have their own approach for encoding settings using ffmpeg, "intelligent recode" suppose to output similar quality like input, that percentage setting suppose to manipulate outcome a bit, so maybe it is CRF mode, but how it mirrors quantizer settings exactly I do not know ...

    VideoRedo uses ffmpeg so they can use quantizers for encoding now

    Inteligent recode could mean CRF 19 (or in that proximity) and percentage could mean logical increments for CRF or other settings to adjust size for outcome, just guess.
    Last edited by _Al_; 9th Apr 2014 at 20:35.
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    Originally Posted by _Al_ View Post
    Looking at those pictures, I do not know what that "Quality Mode" in videoredo does exactly. They have their own approach for encoding settings using ffmpeg, "intelligent recode" suppose to output similar quality like input, that percentage setting suppose to manipulate outcome a bit, so maybe it is CRF mode, but how it mirrors quantizer settings exactly I do not know ...

    VideoRedo uses ffmpeg so they can use quantizers for encoding now

    Inteligent recode could mean CRF 19 (or in that proximity) and percentage could mean logical increments for CRF or other settings to adjust size for outcome, just guess.
    Unless something has changed, videoredo uses mainconcept for h.264 encoding

    ffmpeg would mean libx264, which would actually be preferrable
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    Originally Posted by poisondeathray View Post
    Unless something has changed, videoredo uses mainconcept for h.264 encoding

    ffmpeg would mean libx264, which would actually be preferrable
    VRD tell me they use the Mainconcept encoder for Mpeg2 but not sure about h264

    i am so confused

    i am currently doing a bunch of sample outputs using a 1080/50p m2ts source file, will put the links up when they are done, and you can download them and take a look.

    - output to 1080/25p m2ts (Quality mode)
    - output to 720/50p m2ts (Quality mode)
    - output to 720/25p m2ts (Quality mode)
    - output to Pal dvd Mpeg2 (progressive & interlaced) using TMPGEnc 8000kb vbr
    - output to Pal Mpeg2 (progressive) using VRD 8000kb vbr (vrd wont let me interlace progressive source files for Mpeg2)
    Last edited by glenpinn; 9th Apr 2014 at 20:57.
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    this is a MediaInfo screenshot of a 1080/50p m2ts converted to 720/50p m2ts using the VRD Quality mode preset.

    http://www.mediafire.com/view/qrs576w9aeov0mw/1080-50p_to_720-50p_MediaInfo.jpg
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  15. So they perhaps use 1pass VBR (Intelligent Recode" and Quality Mode" , 1pass setting), not any form of 1pass Constant quality, and bitrate is based on final resolution and that percentage is just to give it some slack, free play in both directions. If that is true, definitively 2pass would be better choice. But this is just guessing again.
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    Originally Posted by _Al_ View Post
    So they perhaps use 1pass VBR (Intelligent Recode" and Quality Mode" , 1pass setting), not any form of 1pass Constant quality, and bitrate is based on final resolution and that percentage is just to give it some slack, free play in both directions. If that is true, definitively 2pass would be better choice. But this is just guessing again.
    this is what one of the Devs emailed to me last nght when i enquired about doing a single or double pass for both h264 and dvd mpeg2 outputs, as i am doing some output testing for them and i had to ask him this question.

    As an FYI, if you do a single pass the H.264 encoder was never very good about honoring the average bit rate as it doesn't really know how to allocate bits for future frames. This is a problem will all single pass encoders, some just hide this fact better than others.

    remember, i can set all my outputs to either 1 pass or 2 passes, i use 2 pass for dvd Mpeg2 always, but until now i used 1 pass for 1080/50p to 720/50p

    VRD also has an output mode called "Forced Recode" as well, but was told not to use it.

    he also told me ages ago that for 1080/50p h264 to 720/50p there is no point in using any higher than 45 to 50% of the source files bitrate.
    Last edited by glenpinn; 9th Apr 2014 at 22:15.
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    Originally Posted by glenpinn View Post

    As an FYI, if you do a single pass the H.264 encoder was never very good about honoring the average bit rate as it doesn't really know how to allocate bits for future frames. This is a problem will all single pass encoders, some just hide this fact better than others.
    Not entirely true either - some encoders have a "lookahead" function so they do know how to allocate for past / future frames


    VRD also has an output mode called "Forced Recode" as well, but was told not to use it.
    This forces a re-encode of the entire thing - basically makes smart rendering usless

    he also told me ages ago that for 1080/50p h264 to 720/50p there is no point in using any higher than 45 to 50% of the source files bitrate.
    That bold generic statement should be ok for "average" cases, "average" source files - but anything with high content complexity will suffer using their / mainconcept h.264 encoding engine . Even using the higher end mainconcept version with all the bells and whistles shows deficiencies when comparing it to the "gold standard" h.264 encoder (x264). This is easy to proove and demonstrate . The vrd version is even worse than other mainconcept implementations, because it doesn't have control over AQ settings - shadow textures, flat areas end up looking poor
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    ok so this Mainconcept encoder they are using is not that good, either for dvd Mpeg2 or h264 encoding.

    is it not right that they are adding their own presets that make it better than it would otherwise be, or doesnt it work like that.
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    Originally Posted by glenpinn View Post
    ok so this Mainconcept encoder they are using is not that good, either for dvd Mpeg2 or h264 encoding.

    is it not right that they are adding their own presets that make it better than it would otherwise be, or doesnt it work like that.

    It's MPEG2 implementation is good, but it's h264 implementation is average (but x264 is much better, proven time and time again, both in subjective assessment, objective metrics)

    For example, if you took something like the well know test sequence parkjoy at 720p50 24Mb/s (as the "source", to elmiminate resizing algorithm differences, encoded with x264 of course so it looks decent to start with), and re-encoded it x264 and mainconcept at 1/2 the bitrate, there would be a HUGE day/night difference, and that's done with the mainconcept SDK. In fact, I 'm fairly certain I posted some of these comparisions in other threads, I'll try to dig up some old comparisons if you're interested. The reason is there is a lot of motion , dark textures and flat areas (water) , and it taxes compression severely. It separates the men from the boys

    Conversely, if you had say, something like a talking heads shot / interview piece, with very little motion, low content complexity then 11-12Mb/s might even be overkill. Compression is very content dependent
    Last edited by poisondeathray; 9th Apr 2014 at 22:53.
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  20. Originally Posted by glenpinn View Post

    As an FYI, if you do a single pass the H.264 encoder was never very good about honoring the average bit rate as it doesn't really know how to allocate bits for future frames. This is a problem will all single pass encoders, some just hide this fact better than others.
    1pass CRF or constant quality, whatever Mainconcept term uses, is just fine, all this time I was just trying to establish if VideoRedo is using that one. Looks like it does not, so sure thing VBR 2 pass is what you should go.

    Not having that mode really sucks , because thinking that you have to encode to certain bitrate is wrong nowadays, just makes no sense, and on the top of that you have to go 2pass. That is why they mask all of this to quality settings, they turn it around for user, at least guessing bitrates for them behind scenes. btw. CRF is such a great tutor for video encoding ...

    but reading pdr, looks like their license version is not top notch anyway ...
    Last edited by _Al_; 9th Apr 2014 at 23:03.
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    well you have better eyes than i do, and i always thought my outputs were fine, many people comment about the video shot with this SDT750 camera.

    i also assumed that h264 and x264 was the same thing, clearly not, so what do you suggest i use, given i edit the video and usually add a title and sometimes an ending credit, which VRD does.

    i downloaded a trial of Sony Movie Studio platinum to see what that is all about, as i also want to add music tracks and probably some little transitions between scene changes to my files if they are needed, and VRD doesnt do that, all i can do is add a text frames between scenes.
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    so i am bashing my head against the wall then.

    i still love VRD 1080/50p m2ts output to dvd Mpeg2, no difference to TMPGEnc that i can tell using 2 pass 8000vbr
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  23. Then use it , and for that H.264 encoding as well, whatever works for you, just give it enough of bitrate. 720p50 , regular camcorder video, 20 seconds, give it 12Mbit, just do some quick tests, how difficult textures behave, play with it for one hour, and then you will have an idea if it is enough ... Nobody is looking at details, everybody is watching the video, not pixels ...

    Use bitrate viewer, check actual bitrate distribution. What you set and what encoder distributed for scene, or better if there is two quite different scenes (day and low light).
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    i am almost finished encoding all my files, i will upload them to Mediafire and you can all download them and offer your opinion.
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    I'm not going to download them - but can tell you from a lot of experience what to look for.

    Look in shadow areas, there will be detail loss even at "100%" . It's just a problem with mainconcept AVC in general . Their higher end versions help with various AQ settings, but still worse than x264

    The other problems in motion will be keyframe popping and temporal stability issues . The allocation between I,P,B frames isn't ideal

    You uploaded a 1080p50 sample in another thread , I re-encoded it with VRD at 100% quality, intelligent. Look under the roof shadows, that's the typical type of "mushy" shadow texture losses you want to look for. It's not a huge difference here , but on more complex sample, the differences will be striking. The "original" for comparison was resized with spline36 algorithm
    Attached Thumbnails Click image for larger version

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    Some people might be thinking - well the shadow detail loss isn't that bad...Maybe only pixel peepers will notice...

    But considering x264 looks like the source at about 65-75% the size of MC without those problems

    Yes, I'm sure you consider those outputs are fine for most people. But there is undeniable texture loss, even at 100%. It's the achilles heel of MC

    And when you actually have high content complexity, lots of motion - the problems and encoder deficiencies are revealed. Surely you can see the difference here ?


    x264 10Mb/s
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    VRD 10Mb/s
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    Originally Posted by glenpinn View Post

    i also assumed that h264 and x264 was the same thing, clearly not, so what do you suggest i use, given i edit the video and usually add a title and sometimes an ending credit, which VRD does.

    i downloaded a trial of Sony Movie Studio platinum to see what that is all about, as i also want to add music tracks and probably some little transitions between scene changes to my files if they are needed, and VRD doesnt do that, all i can do is add a text frames between scenes.


    If you use enough bitrate, almost anything will look good. But why use a file 1.3-1.5x the size if you don't have to ? And even at "100%" quality you can see problems with shadow areas in VRD (not VRD's fault, it's Rovi/MC's fault) (or at least some people can see those problems , you have to trust me if you can't see it) . But those types of encoding issues are almost digital "signatures" that indicate a mainconcept AVC encoder was used

    As an editor , vegas is pretty good . It too is bundled with mainconcept for AVC and MPEG2 (both stripped down versions as well, MPEG2 is fine, AVC not so much), as well as Sony AVC - but there are workarounds to use other encoders such as frameserving (debugmode frameserver), lossless intermediates
    Last edited by poisondeathray; 10th Apr 2014 at 01:02.
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    yes i see the difference in your outputs, both with my file and the one posted above me, because it was pointed out to me, but who would be looking for those deficiencies anyway.

    the main thing for me is that i edit my camera files and they are output without re-encoding the video, and if i add titles/credits or text frames only they are encoded, and these files are my archived copies.

    how do you see the source file overall, given it was shot using a panasonic HDC-SDT750 camera, i think its very good compared to many other cameras in the same class.

    what encoders does Adobe Premier use for dvd Mpeg2 and AVC as that is what my son uses at home, at uni they have to use FCP on their macs.

    the thing is, i dont need all the bells and whistles that come with the cost of some of these more advanced editing tools, but i still want as good as i can get when i output.

    TMPGE and VRD Mpeg2 outputs i am happy with given i dont do it very often.
    Last edited by glenpinn; 10th Apr 2014 at 01:47.
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    Originally Posted by glenpinn View Post
    yes i see the difference in your outputs, both with my file and the one posted above me, because it was pointed out to me, but who would be looking for those deficiencies anyway.
    What's not shown here is the motion issues and flickering quality with I,P,B allocation, since it's a still frame comparison

    But with high enough bitrates, most people won't see these types of issues. But most people think youtube provides great quality . IMO That's not an excuse to give them subpar quality . Most people usually want to display their work in the best possible "light", not be subject to compression issues

    the main thing for me is that i edit my camera files and they are output without re-encoding the video, and if i add titles/credits or text frames only they are encoded, and these files are my archived copies.
    Yes, the smart rendering is the biggest reason for using videoredo . All the other manipulations are usually performed in other software because they are better at it , including resizing, pre-encoding prep

    how do you see the source file overall, given it was shot using a panasonic HDC-SDT750 camera, i think its very good compared to many other cameras in the same class.
    It's ok in daylight conditions



    what encoders does Adobe Premier use for dvd Mpeg2 and AVC as that is what my son uses at home, at uni they have to use FCP on their macs.
    Mainconcept/Rovi as well. FCP uses Apple AVC
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    so Premier has the same encoder as VRD, I would have thought it would be better.

    VRD is soon to release a major upgrade to version 5 of the TV Suite program, and with it has support for importing ProRes, which is the format i will be shooting in when i upgade in several months, and it will sport several enhanced encoding features that will improve outputs, so that is something to look forward to.

    i know if VRD used a better encoder for HD video it will cost more to buy, and i have already asked about their commercial software (broadcast) but its not available, and i wish they had a pro-sumer version that gave us a few added features and better encoder, even if it cost more.

    i do know one thing with that 1080/50p m2ts file you have, when encoded to 720/50p m2ts or mp4 using the new v5 edition the output bitrate using the built in "Quality Mode" preset outputs the file @ 15Mbps where version 4 using an identical profile it puts out around 11Mbps, so i dont know if thats a good thing or not, but that is a 4Mbps increase for some reason, but the Devs have told me that the bitrates should be almost identical, but v5 should be better quality.

    i will be tackling them about it when i get back from my 4 weeks shooting travel videos in asia starting next tuesday.

    Originally Posted by poisondeathray View Post
    But most people think youtube provides great quality . IMO That's not an excuse to give them subpar quality . Most people usually want to display their work in the best possible "light", not be subject to compression issues
    when i return from asia i want to get a professional video channel, either Vimeo as i have now (free) or youtube.

    i want to upload my travel videos in 720/50p m2ts or mp4 so they stay on their servers the way i upload them, so people should be able to download the original file, and not the hacked version that they re-encode it to, which right now vimeo it is 720/25p @ 2Mbps or less.

    i prefer using vimeo over youtube, but youtube may have better support, so i will be looking at youtube more before making my decision.

    cheers
    Last edited by glenpinn; 10th Apr 2014 at 10:18.
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