9 Replies Latest reply: Sep 9, 2013 2:37 AM by Michael@Vision RSS

    How to change variable frame rate to constant?

    CLCTV Community Member

      Hello,

       

      I am exporting a mpeg HDV file that has a constant frame rate to a H264 video (.mp4) video to upload to a web-base video player. I'm actually using the preset in Media Encoder "YouTube HD 720p 29.97".

       

      The online video web interface I use requires a constant frame rate. But when looking at the video in MediaInfo it shows the video file as a variable frame rate. After looking through the settings in Media Encoder I cannot find any option to correct that.  I see where you can change the frame rate and it is at 29.97. So you would think it would be constant but it is not. And it does not have any settings, that I can see, to change from variable to constant. I do see the bitrate settings, but that is not the issue.

       

      I also have Apple Compressor and that successfuly does a constant frame rate, but if possible I'd rather use Adobe Media Encoder. So does anybody know how to change this setting? Thank you

        • 1. Re: How to change variable frame rate to constant?
          JSS1138 CommunityMVP

          Mediainfo is wrong.  PP cannot export variable frame rates.

           

          Try Gspot instead.

          • 2. Re: How to change variable frame rate to constant?
            CLCTV Community Member

            Well I tried Gspot and I couldn't find where it showed it it was a constant or variable frame rate. All it said was 30 fps (but it should be 29.97).

             

            So I tried Media Inspector and it also said "Frame rate mode: variable". It went into more detail and said minimum frame rate 29.970 fps and maximum frame rate: 30.00fps. I also tried the file I transcoded with Apple Compressor with Media Inspector and it read "Frame rate mode: Constant." So two codec readers, MediaInfo and Media Inspector, read that it is a variable frame rate coming from Adobe Media Encoder. The obvious answer will be, well then use Compressor, thing is I don't care for it otherwise and would much rather use Media Encoder if I can solve this issue. Below is the resuts from Media Inspector:

             

            * * * MediaInspector for Mac - Version 2.0, build 896

            * * * ©2012 by Diego Massanti

            * * * MediaInfo Lib by Jerome Martinez

            * * * Raw File Report for Encoder_CBR_NoAdv.mp4

             

            General

            Format                           : MPEG-4

            Format profile                   : Base Media / Version 2

            Codec ID                         : mp42

            File size                        : 150 MiB

            Duration                         : 3mn 56s

            Overall bit rate                 : 5 318 Kbps

            Encoded date                     : UTC 2012-10-03 23:09:47

            Tagged date                      : UTC 2012-10-03 23:09:52

            �TIM                             : 00:00:00:00

            �TSC                             : 30000

            �TSZ                             : 1001

             

            Video

            ID                               : 1

            Format                           : AVC

            Format/Info                      : Advanced Video Codec

            Format profile                   : High@L3.1

            Format settings, CABAC           : Yes

            Format settings, ReFrames        : 3 frames

            Codec ID                         : avc1

            Codec ID/Info                    : Advanced Video Coding

            Duration                         : 3mn 56s

            Bit rate mode                    : Constant

            Bit rate                         : 5 000 Kbps

            Width                            : 1 280 pixels

            Height                           : 720 pixels

            Display aspect ratio             : 16:9

            Frame rate mode                  : Variable

            Frame rate                       : 29.970 fps

            Minimum frame rate               : 29.970 fps

            Maximum frame rate               : 30.000 fps

            Standard                         : NTSC

            Color space                      : YUV

            Chroma subsampling               : 4:2:0

            Bit depth                        : 8 bits

            Scan type                        : Progressive

            Bits/(Pixel*Frame)               : 0.181

            Stream size                      : 141 MiB (94%)

            Language                         : English

            Encoded date                     : UTC 2012-10-03 23:09:47

            Tagged date                      : UTC 2012-10-03 23:09:47

            Color primaries                  : BT.709-5, BT.1361, IEC 61966-2-4, SMPTE RP177

            Transfer characteristics         : BT.709-5, BT.1361

            Matrix coefficients              : BT.709-5, BT.1361, IEC 61966-2-4 709, SMPTE RP177

             

            Audio

            ID                               : 2

            Format                           : AAC

            Format/Info                      : Advanced Audio Codec

            Format profile                   : LC

            Codec ID                         : 40

            Duration                         : 3mn 56s

            Bit rate mode                    : Variable

            Bit rate                         : 317 Kbps

            Maximum bit rate                 : 328 Kbps

            Channel(s)                       : 2 channels

            Channel positions                : Front: L R

            Sampling rate                    : 48.0 KHz

            Compression mode                 : Lossy

            Stream size                      : 8.96 MiB (6%)

            Language                         : English

            Encoded date                     : UTC 2012-10-03 23:09:47

            Tagged date                      : UTC 2012-10-03 23:09:47

            • 3. Re: How to change variable frame rate to constant?
              JSS1138 CommunityMVP

              The obvious answer will be, well then use Compressor

               

              Hardly.

               

              http://www.eventdv.net/Articles/News/Feature/Tutorial-Encoding-H.264-Video-in-Adobe-Media- Encoder-CS5.5-and-Apple-Compressor-4-80446.htm

               

              The obvious answer is that more than one program is incorrectly reporting the frame rate.  Like I said, PP can't output variable frame rate video.  I'm not aware of any application that can.  Variable bitrates, sure.  But not frame rates.  Video is pretty much stuck to only one rate for any given stream.  Any application that's reading it as 'variable' simply isn't reading it correctly.

              • 4. Re: How to change variable frame rate to constant?
                Stan Jones CommunityMVP

                Like I said, PP can't output variable frame rate video.  I'm not aware of any application that can.

                Not common, but it is out there. Here is a link to a description of how mediainfo tags it as variable framerate:

                 

                http://sourceforge.net/projects/mediainfo/forums/forum/297610/topic/5551130

                • 5. Re: How to change variable frame rate to constant?
                  CLCTV Community Member

                  I completly agree Jim, I don't want Compressor to be the answer.

                   

                  And Stan, your link shows that others are fustrated by this too.

                   

                  I did a test were I changed the fps from 29.97 to 30fps. Then in Media Inspector it still showed a variable frame rate with the minimum being 30fps and the max being 30.030fps. So if it is true that it is creating a variable frame rate,  it is only .030 fps. Very minimal I would think?

                   

                  But for me specifically, it is a problem, because we are using a company BrightCove to host our videos, and they are saying my videos have a variable frame rate and don't meet their suggested requiments. BrightCove is a company were you can upload a video file and they make multiple renditions to be able to play on multiple devices.

                  • 6. Re: How to change variable frame rate to constant?
                    Stan Jones CommunityMVP

                    I didn't read that link as frustration: the poster is using matroska files, which provide/allow variable frame rates, and he wanted to understand how Mediainfo was detecting them.

                     

                    I did a quick test. Exported a short bit with the Youtube H264 p720 29.97 preset (the one you are using). Mediainfo reads it as variable frame rate with a nominal rate of 29.97, a min of 29.970, and a max of 30.000. Gspot reads is as 30.000 (not 29.97 as it should).

                     

                    I don't know what to make of that.

                    • 7. Re: How to change variable frame rate to constant?
                      Elliott B. Community Member

                      A client sent me an MP4 file, which should be 23.976.  DaVinci Resolve 9 identifies it as 24.000, which is a problem.  MediaInfo says VFR, min: 23.976, max: 24.000.  To fix this, I transcoded to another codec using ffmbc, but I would like to know how to fix it without transcoding for the sake of both speed and quality.

                      • 8. Re: How to change variable frame rate to constant?
                        Rallymax-forum Community Member

                        It's caused by bad timestamp markers on each frame from the AME shipped h.264 encoder.

                        Grab a trial of x264pro and not only will it look better it'll be constant rate with the correct markers.

                        • 9. Re: How to change variable frame rate to constant?
                          Michael@Vision Community Member

                          I have a very similar problem. Were you ever able to get this resolved? Did x260Pro fix the problem for you?

                           

                          I found that if I used MPEG Streamclip to export the movie, the FPS would say 'Constant', but if I used Handbrake, AME or Squeeze 9, the 'Frame rate mode' always said 'Variable' ! Regretfully, MPEG Streamclip doesn't allow me to choose a 'high' profile, so I had to look for a higher quality encoder.

                           

                          In this case I am trying to export to Amazon, and they are flat out rejecting the file because of the 'variable' frame rate mode.