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Maintaining best quality while transferring HD to SD
  • I have a question maybe some of you more seasoned people can help me with. A friend asked me to enter one of those 48 hour film contests with him. The problem is I typically shoot in 1080p cinema mode on my GH2. The rules for submissions are as follows:

    ... a self-contained SD Quicktime file with no proprietary codecs on either: - data DVD - USB flash drive miniDV playable DVD

    I'm editing and rendering on Vegas Home Studio HD 11.0. I'm wondering if I should be changing the settings on the camera BEFORE even filming, to easier convert to SD..There are also so many output options on Sony Vegas that I'm at a loss on what the best transfer would be to maintain the best quality in standard definition. Wondering if a USB flash drive would maintain better quality than a playable DVD? seems like rather than forcing filmmakers to downgrade their finished product, the contest staff should be upgrading their equipment to handle HD...these are only 4-7 minute videos after all. The finished videos will be screened in a full size theater..something tells me they are going to look not so good.

    Thanks for the help.

  • 28 Replies sorted by
  • Two good affordable solutions: 1) TMPGenc masterworks $90 2) Virtual Dub (FREE!) is good too but for me clunky to use compared to TMPG

    In both cases convert MTS files in Vegas to uncompressed AVI or Cineform (FREE!) before importing to above mentioned programs. You can do it within Vegas but the quality blows.

  • -Normally what I do is output the full resolution master/digital intermediate from Vegas. -Then I open it up in VirtualDub, use the "resize" filter and switch the alogrithm to Lanczos3 and save the output .AVI. - If the DVD authoring program needs a different format, I convert it (sometimes with Vegas) to the desired format.


    This is the "high quality" approach if you are using Vegas because the standard algos. used by most NLEs (GPU based super-scaling in newer Premiere Pro exempted) is bicubic or bilinear, both of which can cause or exacerbate moire patterns when downscaling and do not preserve detail as well as Lanczos3.

  • Looks like @BriancLuce and I basically thought the same thing. :)

  • Here is an illustration of the difference. The first is the original file (1920X1080 with lots of extra sharpening to exaggerate things), the next has been downsampled with Lanczos 3 in VirtualDub and the third downsampled using "Best" settings in Vegas.

    Notice differences in brightness as well as overall detail.

    1920 x 1080 - 4M
    VirtualDub Lanczos3 720x4050000.png
    720 x 405 - 553K
    Vegas 720x405 Best_000000.png
    720 x 405 - 668K
  • @bostonmike You must downgrade your finished product because like DOCchallenge when talking about HD says 'Too many flavors to handle'

    It may seem that supporting 1080p at 24fps is not a big deal, but I like 720p30, and i know editors who prefer 1080i60 1280x1080, and yet another editor only does 1440x1080.. and of course there is the issue of mixing and matching codecs for video.. and then for audio.

  • Thanks a lot both of you guys, I'm going to download that Virtual Dub and Cineform tonight and experiment with them. I notice quite a difference between the Virtual Dub and the Vegas shots above when looking at a larger pic of them. The Vegas shot appears dimmed. Thanks for showing those pics, they demonstrate it well.

    The film contest isn't until May18th, but I want to make sure I've ironed all this out way in advance. Thanks again guys!

  • Thanks PDlumina, that sheds a little more light on their reasoning behind converting to SD.

  • @bostonmike There's a good side to this.. at least you will be in complete control over the creation of the file you send to the contest. An anamorphic DVD should get you very good results (720x480 NTSC 16:9AR), as long as you use enough bitrate (video peak 9.8Mbps, total peak 10.08Mbps) and do a two-pass encode.

    If 9Mbps doesn't seem like a lot of bandwidth, consider this: most TV stations that broadcast an over the air signal (OTA) have only a 17Mbps allowance, and they tend to split that in 2 or 3 depending on how many channels they want to have. So typically, an over the air 'HD' signal is coming down at around 9Mbps. And TV stations that look really good and only have 1 channel, are pumping close to 17Mbps on their 1080i signal... (17Mbps is the stock bitrate of the Panasonic GF2 btw)

  • I agree that a playable video DVD is the best option. Progressive scan DVD can look quite good, even played on an HDTV, when taken from an HD source. Just make sure that the frames are encoded progressively. That will ensure the best possible playback on progressive scan DVD players and PCs. High quality downscaling and high bit rates will help. 1080/24p and 1080/30p are both fine options for shooting in. 30p has that filmic stuttery look, but with a bit less stutter.

  • Thanks a lot guys, I downloaded the GoPro Cineform, but for some reason it wouldn't let me utilize the functions. I'm going to go try that in the future, but for now I'm just glad I figured out how to do it on I edited the clip on my Vegas software in normal HD mode....then I exported it into Virtual Dub and did the resize option and made it widescreen 720x405 Lanczos 3. I'm very happy with the results, its nice and sharp.

    So the test video is 10 seconds long and a total bitrate of 169347kbps..202MB in size. Its maintained the 24 fps look that I like nice and smoothly. The only issue I have is when I burned it on a DVD it plays in slow motion. I'm gong to have to research that problem. Maybe I need to download a high quality DVD transfer software instead of this Windows Media Player. I used a TDK DVD + R 16x disc.

  • Always-ALWAYS-use DVD-R (minus R).. for video DVDS unless your doing a dual layer...which sadly are often hard to find in -R.I dont think this the reason your are having slow mo issues though. Plus R DVDs are are good for data use. I know some half wit is going to argue with me but trust me I have been authoring DVDs for 7 years. Disc brand DOES matter look on other forums and ask. TDk have never been good discs (for me). I prefer verbatim.

    Oh and keep in mind the best way to test a DVD is on a DVD Player (mPeg2 decoder) Computer playback was an afterthought for this format and often times menus and such will behave strange in Windows media player.

  • Also keep in mind that you need to burn ON THE SLOWEST/SLOWER speed when you author DVD dont use 16x on your master Burn at 8x or slower for example.

  • @bostonmike My best guess is that your standalone DVD player (where you should be testing the results as pointed out by No_SuRReNDeR) simply can not keep up with the amount of data the stream has. 169347 kilobits per second come to about 165 megabits/s and that's 'a little' off from the specifications (9216kbps or so for the video stream).

    Look here

    Those specifications allow DVD players manufacturers to have the same compatibility with content on DVD's encoded using those parameters.

    If you stay a bit below 9Mbps on the video stream, use a two-pass encoding, process your footage with a quality software (TMPGenc, Mainconcept, etc), and use AC3 for the audio, then you should have a really good quality DVD playable on most standalone DVD players.

  • This issue " HD to SD" or out to DVD has bean dicussed since HD format was available. Compressor, Sorenzon, Adobe Media Encoder could also do it along with it's NLE.

    Myself, I tried all the way from start to Finish straight out to blue Ray as best as possible. From there I use DVD fab convert it to DVD.

    That's something you could experience for yourself and compare the result with others way.

  • YES YES pdlumina you listen!

    "If you stay a bit below 9Mbps on the video stream, use a two-pass encoding, process your footage with a quality software (TMPGenc, Mainconcept, etc), and use AC3 for the audio, then you should have a really good quality DVD playable on most standalone DVD players."

    -Just keep in mind none of these are perfect and you will not get "Hollywood" quality results using a push button method on down conversion. You will just have to accept good enough or convince the clients that a Blu-ray and web ready QT are the best options.

  • @Tinbeo You mean comparing DVD Fab rescaling to Lanczos3? Which algorithm doe it use? I would be happy to see a comparison, so feel free to use the original frame I posted earlier in this thread.

  • @thepapalias I am no expert and so is my eye ;=) . That solution came to me as an accident just to keep it up with dead line while do a wedding free for my friend. I used to have to work twice, one work flow for Blue Ray, other for DVD. Then here I went , DVD fab have a convert thing could convert the whole blue Ray to Dvd. I gave it to my friend both format. He told me it looks good.

    My 2 cents was just with the eye of a Joe guy. I definitely will try the Film maker view of this way in future. ( master in TMPgenc or Virtualdub )

  • Wide-screen 16:9 NTSC DVD should be 720 x 480. The pixels are not square. Make sure the MPEG-2 encoder is set to 16:9.

  • You're right PDLumina, my DVD player won't even play the video, or even show it at all. I played it on my computer and it played it back in slow motion. It looks like I'm WAY over in size with 169347kbps...not sure what I did wrong there, but I'll have to go back to the drawing board. I guess I need to reduce the quality somehow, how I don't know.

    No_Surrender, I will check out those Verbatim DVD-R when I do my finished product and do a slower transfer speed..funny though, it never even gave me the option of running it at a slower speed, it just did it for me.

    Tinbeo, thanks as well, I'll check out that DVD fab and see what it offers.

    I'm so used to just filming in HD 1080p 24fps, editing in Vegas, running it through Streamclip to make a Quicktime file (as required by the stock video company), and uploading my HD stock video clips without any hitches that I never realized how complex it was to downgrade to SD and put it on a DVD. I thought the hardest part of this film contest was going to be writing the script, setting up the shots and actually filming it, I guess I was wrong. Would I be better off just submitting this thing on a flash drive? I realize I'd still have to iron out the Mbps issue.

    Here is a link to a sample video I did, taken from one of my stock clips. This is 720x405 and I'm wondering, how would I bring that down to below 9Mbps? Thanks!

  • So the link actually played that back in slow motion as well. Funny because when I drag it into my MPEG Streamclip, which is the most readily available option for me to play back an AVI on my desktop, it runs beautiful.

  • As balazer pointed out, you need to make sure to create an anamorphic video in order to have a proper AR upon playback. Do not encode your footage to 4x3 and add black bars to compensate for a 16x9 AR

    This may be more than you wanted to know about making DVD's and the information is out of order, but the ideal way is for you to encode your source file to separate audio and video streams (AC3 or MP2 for audio and M2V for video) and then mux them (put them together into a VOB) with a DVD authoring program.

    I downloaded the AVI you posted and noted a few things: The AR is off and you used back bars to make up for this, so you will be losing resolution on encoding/playback.

    Lets see, if you are used to recording 1080 footage at 24fps and editing the same way, then your resulting file should be a 1080P AVI running at 23.97 (24fps)... however, you mentioned that you edit in Vegas and that makes things a bit easier.

    From the timeline you have the option to render an elementary MPEG-2 file (M2V) at 720x480 and correctly flag it as anamorphic (so on playback everything will look correct). This means every pixel will fill the frame and look streched (unless your player understand the 16x9 flag and displays the proper Aspect Ratio).

    Also from the timeline you can render an MP2 audio file (384kbps is sufficient) or better yet, an AC3 file (192kbps is enough in most cases). Just make sure you use exactly the same IN and OUT points/range when you export the video and the audio, else you'll run into sync issues.

    There's no need to convert your footage to 29,97 for NTSC playback, the DVD player will perform pulldown on the fly.

    The encoder on Vegas is Mainconcept. Go on the settings and make sure to select something like 6Mbps average, 9Mbps maximum and something like 1.5Mbps minimum if the option exists. Also enable 2 pass encoding.

    So then you will be left with an .m2v file and an .mp2 or .ac3 audio file. You can then bring those into your favorite DVD authoring program and create a simple menu-less DVD.

    Also, add some 2 seconds of black before your program on Vegas timeline and the same at the tail. It helps the encoder not to cut-off footage at the start/end and gives you some room after you press play to see the DVD.

    I'll add more if I remember. My favorite DVD authoring programs are (order of preference) DVD-Lab Pro (can't beat the features and flexibility here), DVD Architect (you could have it if you got Vegas as a package), and DVD Studio Pro (OSX only).

    BTW, the test file works OK for me. I used VLC 2.x under Win7. Runs at 23.97fps. WMP has no issues either. You may have a bottleneck with your hard drive transfer rate. After all, the test file is 202 Megabytes and is only 10 seconds long (your hard drive must read a sustained data rate of over 20 megabytes per second)

  • As a sidenote to everyone's post, if you have access to two Mac rigs with AJA Konas or Decklinks, I found that to be the best way to do a downconvert. The image quality is great. I just did a center-crop downconvert for some Walmart spots from a Kona 3 system to a Kona LHe system. After Effects downconvert came in second, but had some aliasing which wasn't in the hardware downconvert. FCP7 had some really bad aliasing, but it would be ok in a pinch (not for broadcast, though). FCPX... worst of the bunch. Waaaay to much anti-aliasing going on there. Image was downright blurry.

  • PDLumina, thank you so much for taking the time to do that walk through with all that info. I think you've finally helped me do it right, but not sure because I think I need different discs to transfer the info onto. I saw this free program called DVD Flick that I'm going to try out to burn the info onto the discs. Yeah I put those black bars in because it was showing some lines on the left and right of the screen when I resized it. I didn't resize it properly.

    What I finally did was set the timeline settings for NTSC DV 24p (720x480 23,976 fps) and then render as DVD Architect 24p NTSC Video Stream. I don't have DVD Architect, but I think it still sets it up as a usable file, as an MPEG file. There is a noticable loss in quality, but at this point I just want to be able to get it on a disc and then I can tweak it a bit. I guess until I download DVD Flick and get a more appropriate DVD disc I won't know for sure. I really appreciate the time you and everyone else took to help me out. Any more advice I'd appreciate it, thanks!

  • ...and after all this, they only accept submissions in 30p, so I'll have to go with the 30p version of what I just did.

  • I hope you mean you shot in 30p, because there is no good way to convert from 24p to 30p.