12 Replies Latest reply on Jul 4, 2009 10:40 PM by allisonf.

    Dropped Frames...

    allisonf. Level 1
      I am editing using Premiere Pro for CS4. I edited some footage on a sequence with the incorrect settings and am now having major troubles exporting the video.
      I shoot HD footage (1280x720, at 24 fps) with a Nikon D90.
      What I did wrong initially was to edit the footage with a frame rate of 25 instead of 24/23.976 . When I realized my mistake, I copied this footage into a new sequence with the correct settings and frame rate.
      However, now the footage is very jumpy and drops frames after it is exported. I looked for a feature that would allow me to remove the distortion due to copying the edited footage between sequences with different frame rates (like Final Cut's "remove attributes", "distort"). However, so far I cannot find anything.


      If this is not the main problem, I am guessing that I am exporting the video incorrectly. The only preset that allows me to have both HDV and 1280x720 (the size of my video) is H.264. However, this same preset only allows for 23.976 fps, not 24 fps (which is what the D90 records in). Could this be the issue?

      Any ideas? I would love some help!
        • 1. Re: Dropped Frames...
          Jim_Simon Level 8

          Slight correction.


          What I did wrong initially was...shoot [video] footage with a Nikon [still camera].



          DSMC is an intriguing concept, but it's not quite there yet.

          • 2. Re: Dropped Frames...
            Colin Brougham Level 6



            The difference between the 23.976fps framerate and the 24fps framerate is really just in how frames are counted, and is not likely to result in any visually-obvious frame dropping. I would suspect that the more likely culprit is in the playback of the encoded H.264 file. What is the bitrate at which you encoded your destination file, and what sort of computer and software are you using to view the file? Is it possible for you to upload a short clip somewhere for closer inspection?

            • 3. Re: Dropped Frames...
              allisonf. Level 1

              Thanks for your feedback Colin.


              I am using a Dell Latitude D630 laptop. I am using both VLC media player and Quicktime to view the file. However these programs play other videos well, without visibly dropping any frames.

              For the bitrate, I did VBR 1 pass for bitrate encoding, with a target bitrate (mps) of 6 and a max. of 10.


              I uploaded a clip to youtube at http://www.youtube.com/watch?v=HXhff0GsOgM . Here the video does not seem to noticably drop any frames... (which is great!) but I'm still confused as to why my computer cannot play this video on my computer when it plays all other ones without any problems!


              Thanks again. I was sure that if the video played so terribly on my computer, the same would be true after I uploaded it.

              • 4. Re: Dropped Frames...
                Colin Brougham Level 6

                It's hard to tell what the issue may or may not be from a YouTube clip, and I'm assuming that you uploaded the H.264 you encoded, and not a different file. However, since it appears that there really aren't any dropped frames in the YouTube clip (where it's likely the file was reencoded by their software), that would seem to indicate that all the frames are actually being encoded and that the problem lies in local playback. QuickTime is pretty flaky when it comes to H.264 playback, especially with higher-bitrate clips, and I'm sort of indifferent to VLC for many of the same reasons.


                Try this: import the H.264 file back into Premiere, and lay it over the top of the section that you've output. Set its opacity to something below 100%, or set the blending mode to Difference. Step through the timeline frame by frame, and look for any obvious discrepencies. That will tell you if frames are being dropped in the encoded file, or if it's just in playback.


                Do you have a location that you could put up the clip you encoded originally, before uploading to YouTube?

                • 5. Re: Dropped Frames...
                  allisonf. Level 1

                  Hmm yes I did upload the H.264 file. Its also at http://vimeo.com/4991999 but I'm assuming that vimeo reencodes the same way youtube does. I don' have another location for the file that wouldn't reencode. Do you know of any?

                  Also, what programs do you use for playback, as opposed to quicktime and vlc?


                  Thanks a lot for your feedback. I will try reimporting the file and checking it.

                  • 6. Re: Dropped Frames...
                    Colin Brougham Level 6

                    Personally, I'm a long-time user of Media Player Classic. Plays just about anything you can throw at it, has no installer, has a really small footprint, and doesn't take over your system like some of the other media players do. You point it at a file, and it plays it... end of story. I'd give it three thumbs up... if I had three thumbs. Not that it's going to solve your playback issue, but it's worth a shot.


                    VLC is OK; I don't necessarily have anything against it, but it seems that with each revision it gets a little bit less focused, and I've had some stability issues with it. Plus, MPC plays everything it plays and more. The one nice thing about VLC is that it does have some transcoding capabilities built-in... but that's another thing that I can't seem to get to work right in the later revisions.


                    And QuickTime... well... I don't even wanna go there. The QuickTime MOV container is actually very capable and powerful, but the Player needs to be dumped out in a gravel pit somewhere.

                    • 7. Re: Dropped Frames...
                      Colin Brougham Level 6

                      OK, I downloaded the video from Vimeo, and while it's more than likely a reencode of your encode, it did reveal something interesting. First off, the info pulled from the file using MediaInfo:


                      Complete name                    : E:\_COMMON_\Test Clips\4137274.mp4
                      Format                           : MPEG-4
                      Format profile                   : Base Media / Version 2
                      Codec ID                         : mp42
                      File size                        : 34.1 MiB
                      Duration                         : 2mn 28s
                      Overall bit rate                 : 1 921 Kbps
                      Encoded date                     : UTC 2009-07-01 05:37:03
                      Tagged date                      : UTC 2009-07-01 05:37:03
                      ID                               : 201
                      Format                           : AVC
                      Format/Info                      : Advanced Video Codec
                      Format profile                   : High@L3.1
                      Format settings, CABAC           : Yes
                      Format settings, ReFrames        : 4 frames
                      Codec ID                         : avc1
                      Codec ID/Info                    : Advanced Video Coding
                      Duration                         : 2mn 28s
                      Bit rate mode                    : Variable
                      Bit rate                         : 1 800 Kbps
                      Maximum bit rate                 : 4 506 Kbps
                      Width                            : 1 280 pixels
                      Height                           : 720 pixels
                      Display aspect ratio             : 16/9
                      Frame rate mode                  : Constant
                      Frame rate                       : 23.976 fps
                      Resolution                       : 24 bits
                      Colorimetry                      : 4:2:0
                      Scan type                        : Progressive
                      Bits/(Pixel*Frame)               : 0.081
                      Stream size                      : 31.8 MiB (93%)
                      Writing library                  : x264 core 67 r1171 2c7cb4c
                      Encoding settings                : cabac=1 / ref=4 / deblock=1:0:0 / analyse=0x3:0x133 / me=hex / subme=6 / psy_rd=1.0:0.0 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / chroma_qp_offset=-4 / threads=16 / nr=0 / decimate=1 / mbaff=0 / bframes=3 / b_pyramid=1 / b_adapt=1 / b_bias=0 / direct=3 / wpredb=1 / keyint=120 / keyint_min=24 / scenecut=40 / rc=2pass / bitrate=1800 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / pb_ratio=1.30 / aq=1:1.00
                      Encoded date                     : UTC 2009-07-01 05:37:03
                      Tagged date                      : UTC 2009-07-01 05:37:04
                      ID                               : 101
                      Format                           : AAC
                      Format/Info                      : Advanced Audio Codec
                      Format version                   : Version 4
                      Format profile                   : LC
                      Format settings, SBR             : No
                      Codec ID                         : 40
                      Duration                         : 2mn 28s
                      Bit rate mode                    : Variable
                      Bit rate                         : 124 Kbps
                      Maximum bit rate                 : 139 Kbps
                      Channel(s)                       : 2 channels
                      Channel positions                : L R
                      Sampling rate                    : 44.1 KHz
                      Resolution                       : 16 bits
                      Stream size                      : 2.20 MiB (6%)
                      Encoded date                     : UTC 2009-07-01 05:37:03
                      Tagged date                      : UTC 2009-07-01 05:37:04

                      What makes me think (positive) that your file is reencoded is that the "Writing Library" is listed as a fairly old build of the open source x264 encoder--I imagine you used AME to export this file originally. In any event, this is only interesting if, well, you're interested in looking at this kind of stuff (I am, anyway!). Ahem...


                      After I downloaded the file, I played it back in MPC, and it played pretty much the same as it did on Vimeo... this is more or less to be expected. However, I noticed something interesting during playback, which I explored a little more in the next part.


                      Finally, I imported the MP4 file into Premiere, where I'd have frame-by-frame playback control. This is where I confirmed what I thought I saw in the MPC playback. If you load the clip (at least this reencoded version--I have no idea whether this is happening on your original or not, so you'll have to experiment) into the source monitor and step through one frame at a time, you'll quickly see something odd: after 23 frames, the 24th frame is a repeat of the 23rd! This happens over and over, every second: 23 changing frames followed by one that is the same as the frame immediately preceding it. Now, I can't tell if frames are being dropped, because I have no way of knowing what's missing; you'd have to confirm that by comparing the encoded file to the originals in the timeline as I described previously.


                      So, what does this all mean? I really can't say, unfortunately. Something fishy is going on. Did you by any chance accidentally export from the 25p timeline to a 24p destination file? That could have the effect I'm seeing, but then again, maybe not.


                      Do a little bit of tinkering with your project and the encodes, and see what you can uncover. I believe it's a simple thing; it's just hard to get to the bottom of it without looking directly at the issue.

                      • 8. Re: Dropped Frames...
                        allisonf. Level 1

                        Wow I see exactly what you mean. None of the frames are being dropped- its just that problem of the frame repeating every second. I also downloaded the vimeo file and compared it to the file I uploaded. Both have the same problem.

                        But I double checked and am sure that I exported the file from the correct timeline, not the 25p one.

                        So, I looked at another brief experimental video I did. Its at http://www.vimeo.com/5106819 . This video does not seem to have the same problem, as far as I can tell. The only thing I did differently with this video was that I did not originally edit it with the 25p timeline...

                        Thanks so much for your help!

                        • 9. Re: Dropped Frames...
                          Colin Brougham Level 6

                          Do you still have the project that you edited the original video in (the Captree one)? If so, I'd suggest checking there to see if the same frame-repetition anomaly is present. If it is, something is happening in the interpretation of the footage. If it's not, something is happening on export.


                          OK, so you exported from the 24p timeline. Now, did you copy and paste the clips from the original 25p sequence, or did you nest the original sequence in the 24p sequence? If you copy/pasted the clips, I can't see any way that the clips would be misinterpreted automagically by Premiere, unless it was intentionally or accidentally done by you. Nothing should changed with the source clips if they're used in a sequence with one timebase, and then another--they are what the are. Now, if the 25p sequence was nested in the 24p sequence, it is conceivable, or at least possible that that is the source of the weirdness.


                          I checked the other video you just linked to; as you said, I don't see the frame-repetition or any apparent skipping happening. So whatever you did there, worked correctly.


                          Odd stuff, but we're getting closer...

                          • 10. Re: Dropped Frames...
                            allisonf. Level 1

                            Hey Colin,


                            I'm sure I just copied and pasted the footage between the sequences because I actually do not know what "nesting" the sequence means. : )


                            I took a look at the original project file. The frame repetition occurs in the original timeline in which I edited the footage with the 25p setting. However, it does not occur in the other sequence with the 23.976p setting.

                            So, I reexported the sequence with correct settings, even though I was pretty sure that's what I did before too. I imported this new file and do not see the same frame repetition problem. So I guess that other file really was from the 25p footage. I exported and deleted so many versions I just ended up mixing them up!

                            I am replacing the vimeo file with this new file. See if you think it works!




                            ps The file still plays terribly on my computer and skips frames, I guess I'll have to download that other media player you suggested!

                            • 11. Re: Dropped Frames...
                              Colin Brougham Level 6

                              When you "nest" a sequence in Premiere, it refers to using an original sequence as though it were a single clip, and dropping it into a new destination sequence. Any changes you make to the original sequence are carried through to the new sequence, and you can also effects and do transformations to the nested sequence. This is an easy way to, for instance, apply a consistent look to a finished sequence by applying a color correction filter to the nested sequence; it's much easier to manipulate ONE effect instance, then multiple instances on multiple clips, if you change your mind about how the effect looks. This is common practice for changing frame rates and frame sizes, as well. Check out the help file for nested sequences for some more information.


                              Glad to hear that revisiting the original project was fruitful, at least from a "gettin' to the bottom of it" standpoint I checked out the new video on Vimeo, and as you indicated, I didn't notice any duplicated frames. One thing that was interesting, though, is that the frame rate is now reported as "24.000fps" instead of "23.976fps" as in the previous version of the video. Not necessarily a problem--in fact, it's probably the correct frame rate to use given the source material--but I'm curious about what your sequence timebase was (24p or 23.976p) and what your export frame rate was. Even though Vimeo reencodes, I don't think it'll do any frame rate adjustments, so whatever you feed it is what you get online. In any respect, 24.000fps is perfectly fine and appropriate for videos destined for web playback. Broadcast would be a different story, but I don't think that's your goal.


                              So, the final problem (or so it would seem): stuttery playback from the local file. Since the Vimeo versions show all frames correctly, that indicates that all frames are present in the H.264 versions you originally encode from AME. In other words, if the frames aren't in the source, they're not going to be in the destination. This rules out a problem with the file you encode, and points to an issue with either a) the playback software you're using or b) your computer. You listed your computer model, but that doesn't tell us anything about the actual specfications and capabilities of the machine, unfortunately. It may just be that the 6-10Mbps videos you're encoding are too much for your computer to handle, or more likely, they're too much for the players you're using to handle. One test you could do would be to export the same video to the same settings, but use a lower bitrate--say 1000-1500Kbps (1.0-1.5Mbps). If those play back fine, keep bumping up the bitrate until you see frame dropping--that's about all you can do. H.264 is a very resource-intensive codec, and certain parameters can bring even a well-equipped machine to its knees. If you look at the report I posted about the Vimeo-reencoded file, you'll see that the bitrate (average) is 1800Kbps, with a maximum of about 4500Kbps. The file still looks decent (not pristine), so you could probably export at a bitrate of about 2000Kbps (2.0Mbps) and get a good looking file, especially if you use 2-pass VBR encoding.


                              Beyond that, try Media Player Classic and see if it gives you any better results. The frames are there; it's just up to your computer to be able to show them. Also, a good diagnostic/detective tool that I find extremely useful for web video is MediaInfo. I use it quite often to see what other people are doing to make videos look good (or bad, in some cases). Good luck!

                              • 12. Re: Dropped Frames...
                                allisonf. Level 1

                                Yea one of the things I was trying out when I couldn't get  the video to play correctly was exporting with the same settings but trying both 23.976p and 24p. (23.976p because that was the setting of the timeline and 24p because my camera shoots in 24p)

                                Thanks for your help Colin!