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Thread: I've been trying for days. . .

  1. #1

    Default I've been trying for days. . .

    I don't know what I'm doing anymore.


    I'm trying to convert an MP4 video I recorded with Open Broadcaster Software to a series of PNG frames. I first tried Adobe Media Encoder CS5. Unfortunately, I found the exported image quality unsatisfactory.


    Here are some examples:


    Below is a screenshot of the movie I took with VLC Media Player.
    Exhibit+A.jpg


    In my opinion, the quality here is flawless. Zoom in -- the pixel edges are quite pronounced.

    Below here is a frame I exported with Adobe Media Encoder.
    Exhibit+B.jpg


    If you zoom in, you'll notice annoying little pixel echos. I feel like the image has been ever so slightly scaled and then re-scaled.

    Here is a comparison. You'll have to open the image in a new tab to see it.
    Exhibit-C.gif


    Notice the VLC screenshot is quite crisp and precise. I'd like to see that same pixel precision on every frame I export.

    It was quite apparent I was losing quality with AME.

    I tried many, many times to match the source video's settings when I exported. No luck.
    Exhibit+F.jpg


    It was already clear to me VLC was capable of outputting the frames I needed with the quality I wanted.
    I mean, it took perfect video screenshots.


    So I tried to export every frame of the movie using VLC's Scene video filter.


    I set the 'Recording ratio' to '1' so that VLC would export every single frame.


    Apparently, VLC is unable to export every single frame. Whenever it tries to do this, most of
    the exported frames are corrupt and empty. This bug has been known since 2008, and
    still remains unfixed.
    exported images corrupted.jpg

    After this, I tried numerous different programs to no avail. I tried AVS Video Editor,
    VirtualDub, VirtualDubMod, MediaCoder, Convert MP4 to Any and a few others I've
    already forgotten.

    None of them can convert an MP4 video to a series of lossless PNG images.

    Next I looked at ffmpeg.

    This thing is beyond me. I have to use the Command Prompt?


    People say it can do the job, but I have no idea how to work it.


    Well, to summarize, I need a program that can export either .png images or .tiff images from an MP4 video.


    I want a program that can do this with zero compression. Does anyone know of one? VLC would work if it could just
    export every frame.


    I just want a series of perfect, crystal-clear screenshots. I'd appreciate any help.

  2. #2

    Default

    Is the source video interlaced or progressive?

    The pictures you uploaded are tiny and I can't really see any resolution within them.

  3. #3

    Default

    Quote Originally Posted by TheUninformed View Post
    Next I looked at ffmpeg.
    This thing is beyond me. I have to use the Command Prompt?
    People say it can do the job, but I have no idea how to work it.
    I have used ffmpeg several times to convert a video into a series of PNG files. Yes, it assumes the user has some experience or knowledge of the Command Prompt.

    After installing FFMPEG; perhaps the easiest way to do it is:
    1. Copy the video into the folder where "ffmpeg.exe" is located.
    2. Open a Command Prompt and navigate to the same folder (where ffmpeg.exe and your video are).
    3. Enter the relevant command.

    In the following example, my video is named "video.mp4" and I want the output to be sized "1280 by 720", and the output PNG files to be sequentially numbered.

    ffmpeg -i video.mp4 -s 1280*720 image%d.png

  4. #4

    Default

    Quote Originally Posted by TheUninformed View Post
    After this, I tried numerous different programs to no avail. I tried AVS Video Editor,
    VirtualDub, VirtualDubMod, MediaCoder, Convert MP4 to Any and a few others I've
    already forgotten.........

    ............None of them can convert an MP4 video to a series of lossless PNG images.
    To get best results you ideally need to change your MP4 file into an 'intraframe' format before you try and export as a png sequence. That way you will not be relying on your chosen software to try and create a series of independent 'complete' frames on the fly, as it were.

    MP4 uses highly a compressed 'GOP' (Group of Pictures) structure which only has a defined 'keyframe' every few frames (the exact number varies). All the other frames look backwards and forwards to adjacent frames, to try and decide which 'unchanged' information doesn't need to be stored again.

    Generating a series of independent .png images needs to undo that process, and recreate new frames where they don't actually exist in the original. How well different softwares do that will of course vary.

    In your situation I would convert your file into a high quality Grass Valley HQ or HQX intermediate file, import that into Virtualdub and then 'Export - Image Sequence - png' from Virtualdub. Should give you excellent quality results.

    You can download the latest versions of the Grass Valley AVCHD2HQ converter and HQ/ HQX codecs for free by registering a free account with Grass Valley, or you can find slightly earlier versions on their Taiwan website without registering:

    http://www.canopus.com.tw/PC/Downloa...y_(v4.10).html


    http://www.canopus.com.tw/PC/Downloa...ack(v652).html

  5. #5

    Default

    Quote Originally Posted by rogs View Post
    To get best results you ideally need to change your MP4 file into an 'intraframe' format before you try and export as a png sequence. That way you will not be relying on your chosen software to try and create a series of independent 'complete' frames on the fly, as it were.
    I do not agree. And think installing the "Grass Valley" software is not a useful solution.
    I don't know why VLC fails, but I was surprised the poor quality from the Adobe Media Converter. I assume the OP used the converter's settings for "Maximum Render Quality". Perhaps the Video file has an unusual format.

    I note the OP has also posted exactly the same question here:
    http://forum.videohelp.com/threads/3...ages?p=2344809

  6. #6

    Default

    Quote Originally Posted by TimAndrews View Post
    I do not agree. And think installing the "Grass Valley" software is not a useful solution.
    You are of course entitled to your opinion -- even though, in return, I don't happen to agree with you (unsurprisingly perhaps!)

    I enjoyed my early adventures with video editing using DV as a format, and inevitably got spoilt with 'butter smooth' timeline scrubs, real time previews and frame accurate cutting etc....

    Trying to edit long GOP formats like MP4 came as a real shock.... especially any attempts with a less than modern computer.... And tricks like 'smart rendering' which involved 2 colour space conversions around the edit points, but none around the rest of the file, I found very strange.
    Talk about taking a step backwards!

    So I took the approach taken by many professionals, and converted my long GOP files into a high quality intermediate format. I could have chosen Cineform.. but went for Canopus HQX. Both codecs are now freeware, and the Canopus codec came with a very useful and comprehensive converter utility... also free.

    And I was back to the same kind of easy editing that I had previously enjoyed with DV files. And of course that included frame accurate cuts, because I was now using an intraframe format.

    But, as you have suggested, it may not suit everyone.

    As it's free though, it might be worth a try? - especially if if you are trying to find an easy way to create a high quality png sequence.
    Probably a good idea to start with an intraframe format, I would suggest?.....

  7. #7

    Default

    Quote Originally Posted by rogs View Post
    You are of course entitled to your opinion -- even though, in return, I don't happen to agree with you (unsurprisingly perhaps!)
    Yes. I am sorry, I was unclear. I think that if one wants to create an intermediate file, it is better to decode it as a fully uncompressed file; rather than having to use the Grass Valley software. Sadly, none of us yet know anything about the OP's file format. So we cannot test the theory.

  8. #8

    Default

    Quote Originally Posted by David Partington View Post
    The pictures you uploaded are tiny and I can't really see any resolution within them.
    Actually, I'm positive I uploaded very large images. I don't know why they're now tiny.

    Anyway, ffmpeg worked perfectly! Thank you, everyone!

  9. #9

    Default

    Quote Originally Posted by TimAndrews View Post
    Yes. I am sorry, I was unclear. I think that if one wants to create an intermediate file, it is better to decode it as a fully uncompressed file; rather than having to use the Grass Valley software. Sadly, none of us yet know anything about the OP's file format. So we cannot test the theory.
    We now have the OPs comments on his way forward, so our considerations are now largely academic.

    Over the years I've tried out most file types, and while of course uncompressed obviously cannot be bettered, the sheer file sizes are pretty scary. for example, I had a small 3.6MB mp4 test file. Only about 9 seconds long. The HQX version was about 25MB. The uncompressed version was 172MB !.......
    But the HQX version appeared to be identical visually. Clearly it's not lossless, but it really is an excellent intermediate. Much more versatile than the previous Canopus HQ format, in my experience. And with smaller file sizes! Up to 10 bit - no size restrictions - alpha channel. A very under used format, IMHO.
    Works very well with AVISynth scripts and Virtualdub as a VFW coded if required, and very resilient to any multi-generational editing losses.

    And of course much smaller files than uncompressed!... or even 'lossless' codecs like Lagarith or Huffyuv. I even find it more versatile than Cineform ... which is also a free codec these days!

    And, no, I don't have any connection with Grass Valley or Canopus.... I just find the way they do things suits my workflows....

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