tool to check video files for freezes? (downloaded with letmeatit)

[schmutzbrust]

Hello,

i downloaded video files with the tool "letmeatit". I noticed, that my files always freeze for a few moments. This is very random. Everytime i download it again, the freezes are on another place. :/

Can i check my videos with some kind of tool, that shows me the exact spot of the freezes? The videos are quite long, so i can't check them myself after every download attempt. :/ Or did i make something wrong with letmeatit?


sorry for english

Thanks a lot

[johnmeyer]

If the frames repeat exactly, then it is very easy to find the frame numbers where duplicates occur using an AVISynth script.

Here is some old code I had lying around. If you only need to find true duplicates, set the blankthreshold value to a really small number, like 0.1.

#This script finds exact duplicate frames and outputs the frame numbers
loadPlugin("c:\Program Files\AviSynth 2.5\plugins\MPEGDecoder.dll")
loadPlugin("c:\Program Files\AviSynth 2.5\plugins\dgdecode.dll")

#Set blankthreshold to a really low value, like 0.01, if you only want to detect true duplicates
global blankthreshold=3

filename = "e:\output_duplicate_frames.txt"
AVISource("e:\fs.avi").killaudio()
i=AssumeBFF.ConvertToYV12

#This line below will output EVERY frame that is below threshold, which results in LOTS of frames
#Normally you don't do this, but it is included for those who want this capability.
#WriteFileIf(last, filename,  "(YDifferenceFromPrevious(i)<=blankthreshold)", "current_frame+1", append = false)

#The line below writes the FIRST frame that falls below the threshold
WriteFileIf(last, filename,  "(YDifferenceFromPrevious(i)>blankthreshold)&&YDifferenceToNext(i)<=blankthreshold", "current_frame", append = false)

#Use this instead of WriteFile in order to determine blankthreshold
#ScriptClip("Subtitle(String(YDifferenceFromPrevious(i)))")

[schmutzbrust]

Thanks a lot for your post and the script. Unfortunately it won't regognize the freezes. :/ Tried several values. :/

Maybe it's not a freeze in a classic way, i don't know whats the problem.

[johnmeyer]

Thanks a lot for your post and the script. Unfortunately it won't regognize the freezes. :/ Tried several values. :/

Maybe it's not a freeze in a classic way, i don't know whats the problem.

You have to post a few seconds of un-edited video so we can see what you actually mean by "freeze." Normally a freeze is caused by duplicate frames, but if my script didn't work, then there is something else going on.

So, post a clip.

[schmutzbrust]

Here's a 1 min Sample (look from 0:35)

https://1fichier.com/?bx3qtex2ryv4k3ocmvs2

[Selur]

ffmpeg -v error -i "Path to file" -f null -

reports:

[h264 @ 0000012873e5a100] Reference 7 >= 2
[h264 @ 0000012873e5a100] error while decoding MB 68 20, bytestream 167
[h264 @ 00000128741e2340] error while decoding MB 96 14, bytestream -9

on files without an error it reports nothing.

Cu Selur

[schmutzbrust]

Is this also an AviSynth script? Because i got an error message:





deleted the "-" at the end, i got this:

[Selur]

No that was a command line to use FFmpeg.

[jagabo]

ffprobe shows the video is VFR. Most frames are displayed for ~33 ms. But frame 1108 is displayed for 5100 ms, and frame 1134 is displayed for 5167 ms.

A slight mod of johnmeyer's script:

#This script finds exact duplicate frames and outputs the frame numbers
#loadPlugin("c:\Program Files\AviSynth 2.5\plugins\MPEGDecoder.dll")
#loadPlugin("c:\Program Files\AviSynth 2.5\plugins\dgdecode.dll")

#Set blankthreshold to a really low value, like 0.01, if you only want to detect true duplicates
global blankthreshold=0.1

filename = "test_duplicate_frames.txt"
LWlibavVideoSource("test.mkv", fpsnum=30000, fpsden=1001) # converts to CFR
i=last

#This line below will output EVERY frame that is below threshold, which results in LOTS of frames
#Normally you don't do this, but it is included for those who want this capability.
#WriteFileIf(last, filename,  "(YDifferenceFromPrevious(i)<=blankthreshold)", "current_frame+1", append = false)

#The line below writes the FIRST frame that falls below the threshold
WriteFileIf(last, filename,  "(YDifferenceFromPrevious(i)>blankthreshold)&&YDifferenceToNext(i)<=blankthreshold", "current_frame", append = false)

#Use this instead of WriteFile in order to determine blankthreshold
#ScriptClip("Subtitle(String(YDifferenceFromPrevious(i)))")

finds duplicate sequence (after converting to CFR) starting at frames:

498
501
504
507
1106
1283
1285
1496
1499
1502
1505
1508
1797

All verified.

[schmutzbrust]

@selur

Sorry, my bad. Now it worked:





@Jagabo

Thanks, but how i set the path to my video file? At the moment it says: Script error: There is no function named 'LWlibavVideoSource'
i assume, this is for avisynth?

Or is there a way to make a batch file out of it, so i just drag the video to it? If it works, i'll have to test a lot of them (videos) :/

[jagabo]

First you need to download and install the LSmash source filter for AviSynth. http://avisynth.nl/index.php/LSMASHSource

[jagabo]

Here's an example batch file (you can drag/drop your sample on it) that will produce an AviSynth script and execute it via ffmpeg to produce the list of duplicates:

echo LWLibavVideoSource("%~d1%~p1%~n1%~x1", fpsnum=30000, fpsden=1001) > "%~1.avs"
echo WriteFileIf(last, "%~dpn1.dups.txt",  "(YDifferenceFromPrevious(last)>0.1)&&YDifferenceToNext(last)<=0.1", "current_frame", append = false)  >> "%~1.avs"
ffmpeg -i "%~1.avs" -f null -
pause

But there's an obvious problem: the frame rate of a video may not be 30000/1001. You would have to extract that information from the video first then add it to the batch file. There are many other reasons why such an automated process could fail too.

[Vidd]

Download each video twice. Check if the CRC of the videos match. If they are the same, the videos downloaded correctly and the duplicate can be deleted. If the CRC differs, download the video for a third time. Compare the CRCs for two that match. Delete the wrong CRC video, as well as the duplicate.

While this method consumes more bandwidth and time, it ensures that it downloaded without errors in the stream.