VideoHelp Forum

Our website is made possible by displaying online advertisements to our visitors.
Consider supporting us by disable adblocker or buy Replay Video Capture or PlayON and record Netflix!
+ Reply to Thread
Results 1 to 7 of 7
  1. I muxed from M2TS 1080p to MKV. The M2TS file has got 12719 kBit/s audio stream. Now after changing the container via muxing with mkvmerge, the video bitrate is now decreased by 11887 (about 7%)! I thought that shouldn't be the case as changing the container doesn't encode the video, or at least a vastly smaller difference of like up to 1%. So why is this?

    Okay, there may already be some threads explaining this problem and referring to "overhead". I'm not familiar with some terms. But in my video I can even see a little difference. There occur horizontal violet lines all over the video when frames are switching because of rapid camera movemend. These lines may be visible very very weak and only be noticed when concentrating on them and immediately having the eyes in front of the monitor, but they are still present. Should this be? Is this normal? I mean it doesn't bother me at all, but I am still interested in "fixing" it if possible.
    Last edited by draig-llofrudd; 3rd Dec 2016 at 16:01.
    Quote Quote  
  2. How did you measure the video bitrate?

    Possible reasons:
    1. mkvmerge removes filler NALUs
    2. mkv container overhead is much smaller than transport stream overhead
    3. you did not measure correctly
    4. a mix of 1, 2, 3
    Quote Quote  
  3. Click image for larger version

Name:	Unbenannt.jpg
Views:	183
Size:	108.8 KB
ID:	39795

    This is where I've looked it up. And sorry, the M2TS bitrate is a little more than 12719. My bad. Is this how I can compare it or must I do a calculation? And even if, why can I see a difference in the video? By the way, this doesn't affect all muxes, but mostly the 1080p videos.
    Quote Quote  
  4. Dinosaur Supervisor KarMa's Avatar
    Join Date
    Jul 2015
    Search Comp PM
    Mediainfo will give you more info on your files.
    Quote Quote  
  5. Oh, you were talking about overall bitrate, not specifically about video track bitrate. It's ok how you compared. Just looking at the file size should yield the same result without relying on any software doing deeper analyses.

    Originally Posted by draig-llofrudd View Post
    And even if, why can I see a difference in the video?
    You are probably imaging things or it's just a problem with your player. If you are still unsure you could compare them more systematically, e.g. decode and compare checksums of raw decoded data or compare in AviSynth. ( or for example)
    But IMHO that will be a waste of your time. There will be no difference.
    Quote Quote  
  6. The decoded stream will be identical. Just demux the elementary video stream and compare (e.g. tsmuxer for ts or mkvextract for mkv). That is the proof. MKVMerge will remove things like sequence headers, so there might be a few bytes difference, but the actual decoded video stream will be the same. If you want to triple check, you can do a per frame psnr check, that is definitive proof.

    It might "look" different depending on how the player is configured. You mentioned "1080p", but some players are configured to deinterlace transport streams
    Quote Quote  
  7. As sneaker already mentioned, I would waste my time comparing the videos unnecessarily since it doesn't bother me, because the difference is practically zero. But I will leave a screenshot in a few minutes just to show you what I mean.

    Edit: Well, it only appears in motion of the pictures, so I can't make a screenshot. It's quite distinct. But let's leave it by that. Here's what it roughly looks like (did it with GIMP):

    Click image for larger version

Name:	Unbenannt.jpg
Views:	143
Size:	52.4 KB
ID:	39796
    Last edited by draig-llofrudd; 3rd Dec 2016 at 17:38.
    Quote Quote  

Similar Threads