Post Reply Stuttering & missing frames
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Posted 10/4/15
I've been a Crunchyroll subscriber for about three months now. I noticed some stuttering in a number of shows. (I am just watching on my PC.) Today I decided to dig in a little and do a frame-by-frame dump of a video, and see if this is an issue with my computer or Flash player, or the video itself. What I ended up with is:


http://stuff.aaron-kelley.net/2015/10/Naruto.gif <-- Full-size version (720p)

Here is a slowed down frame-by-frame dump from Naruto Shippuuden 432 (http://www.crunchyroll.com/naruto-shippuden/episode-432-the-loser-ninja-684441) at about 15:43. I put the frame number in the bottom right corner. You can see...

Frame 1 - normal
Frame 2 - normal
Frame 3&4 --- they are the same, it looks like frame 4 was included twice and frame 3 was dropped
Frame 5 - normal
Frame 6 - normal
Frame 7&8 --- same story, frame 8 included twice, frame 7 dropped

...and so on...

If you watch this part of the video, you can notice a bit of a stutter as the "camera" pans by. This issue actually occurs throughout the video but is most obvious during a "camera pan".

This happens in a number of recent Naruto episodes --- I'd say at least half of them, and often the video starts out fine and then the issue starts occurring later on in the episode. I've also noticed it in Fairy Tail.

To be clear. This issue is not related to bandwidth or some PC issue. The frame issue above is baked into the video. I confirmed it on both the 720p and 1080p version. I suspect that every single one of you will see it if you look --- however, how obvious it is depends on how sensitive you are to a single-frame stutter. For me, this leads to a really obnoxious experience, watching videos that have this issue.

I did some searching online and not many people are complaining about this. I'm surprised since it appears in a lot of videos as far as I can tell. Does anyone else notice this in the shows that they watch?

I paid for a year and I'm sorry because I expected the videos to be quality encodes. I know I should have checked it more carefully first, but I won't be renewing if this doesn't get fixed.
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Posted 10/4/15
This isn't an issue, this is when you upgrade from 24fps (the standard) to a higher FPS (I think they play at 29.96 FPS, but I could be wrong).
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Posted 10/4/15
It's not a bug, it's a feature?
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Posted 10/5/15 , edited 10/5/15
I don't buy it. If the source video is 24 FPS, they should put up a video with 24 FPS. Monitors with a higher refresh rate can play it back without stutter. In this case, the duplicate frames are not the result of playback, they are encoded in the source video.

Even so, there are some issues with that theory.

* Converting from 24 FPS to 30 FPS means adding a duplicate frame after each four frames of the source, so there would be a 5-frame sequence with a duplicate frame in each one. Here I am clearly seeing a four frame sequence.

* In this case, there are missing frames being lost. Look at the animation above and you will see that, at frames 3, 7, 11, and 15, the "pan" jumps further ahead than in the other frames. This is because frame 3 is lost, and frame 4 is shown twice.
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Posted 10/5/15 , edited 10/6/15
It's bad encoding. To convert 24 (23.976) fps, which is the standard at which most content is animated at, to 30 (29.96) fps which is what most TV broadcasts are, a process called telecine is used, most commonly in a manner called 3:2 pulldown. To overly simplify the process parts of 2 frames (called fields) are combined to make an extra frame.

If left as is and played on a monitor, 2 out of every 5 frames will have annoying lines through them, especially visible in motion. To remove this, a process called inverse telecine is used. Normally, the extra fields are matched up to the originals to create a single frame. The result is 4 original frames and 1 duplicate frame and video that runs at 30fps, which is evident in the sample above.

Here's where the encode goes wrong, there is supposed to be another step in the process. Usually, one would perform what is called decimation, which drops the extra frame and returns the video back to 24fps. If the video has a constant 3:2 patter, this can be done perfectly. Sometimes the pattern is inconsistent, usually do to video editing such as adding commercials and such. Still, most video processing can return a reasonable result with a lot less noticeable judder or jerkiness than just field matching and leaving it at 30fps.

I can't say if they leave it at 30fps for a reason, some devices may require it. In most situations I know of, there are better ways to handle it but I've seen this issue on other sites so I'm inclined to believe there is some reason not to decimate.

Edit: Wiki page for 3:2 pulldown has a good pic to illustrate the process.
https://en.wikipedia.org/wiki/Three-two_pull_down

Edit 2: Based on aaron44126's post, I think it's possible the decimation is just missing the correct frame. Somewhere it gets the cadence screwed up, probably after a video edit, and does not reset. It's possible the pulldown is 2:3:3:2 or just changes the pattern somewhere. In any event, proper IVTC should still be possible.
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Posted 10/6/15
Thank you for your informative response. You've confirmed my suspicion that this is an encoding issue and offered a bit more of an in-depth explanation (I don't understand the nuances of framerate conversion).

I'm going to complain to Crunchyroll (but I don't have much hope that they'll fix anything).
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Posted 10/6/15

aaron44126 wrote:

Thank you for your informative response. You've confirmed my suspicion that this is an encoding issue and offered a bit more of an in-depth explanation (I don't understand the nuances of framerate conversion).

I'm going to complain to Crunchyroll (but I don't have much hope that they'll fix anything).


When they respond with a template email blaming your computer in a week or two, come back and rant to us... we won't be able to fix it, but it'll make you feel better to get it off your chest. (^_~)
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Posted 12/6/15 , edited 12/6/15

aaron44126 wrote:

I've been a Crunchyroll subscriber for about three months now. I noticed some stuttering in a number of shows. (I am just watching on my PC.) Today I decided to dig in a little and do a frame-by-frame dump of a video, and see if this is an issue with my computer or Flash player, or the video itself. What I ended up with is:


http://stuff.aaron-kelley.net/2015/10/Naruto.gif <-- Full-size version (720p)

Dadgummit. I'm also noticing it, now that CR video actually streams correctly sometimes (i.e. now that the st...u...tt...er...ing isn't always much worse than just this). It's all your fault for pointing it out, obviously. (^_~)
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Posted 12/6/15

arimareiji wrote:

Dadgummit. I'm also noticing it, now that CR video actually streams correctly sometimes (i.e. now that the st...u...tt...er...ing isn't always much worse than just this). It's all your fault for pointing it out, obviously. (^_~)


I've always noticed it from when I first started using Crunchyroll, but I honestly didn't know if it was normal or not. Ugh, when will their engineers upgrade their shitty player already..
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Posted 12/10/15

Lemontitties wrote:


arimareiji wrote:

Dadgummit. I'm also noticing it, now that CR video actually streams correctly sometimes (i.e. now that the st...u...tt...er...ing isn't always much worse than just this). It's all your fault for pointing it out, obviously. (^_~)


I've always noticed it from when I first started using Crunchyroll, but I honestly didn't know if it was normal or not. Ugh, when will their engineers upgrade their shitty player already..


Yea I could have a ggod day or bad but without changing anything yra you can get the form letter saying it's me !

But actually it has been better this week until another common problem the 3rd video when it freezes . Before I start my cache history all cleaned so who knows anymore!
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