Filter to detect video glitches

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Filter to detect video glitches

Venkateswaran.S
Hi all,

I wants to detect glitches in my video. Is there any filter to achieve it.?
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Re: Filter to detect video glitches

Michael Koch
Am 10.03.2019 um 08:22 schrieb Venkateswaran.S:
> Hi all,
>
> I wants to detect glitches in my video. Is there any filter to achieve it.?

How does the glitch look like? It it's black, you could try the
blackdetect or blackframe filters.

Michael

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Re: Filter to detect video glitches

Venkateswaran.S
Glitches are video aftrifacts created by poor encoding/decoding or problem
in network connection while playing online video. It can't be detected by
blackdetector. Please find the attached image for your reference.

On Sun, 10 Mar 2019, 14:48 Michael Koch, <[hidden email]>
wrote:

> Am 10.03.2019 um 08:22 schrieb Venkateswaran.S:
> > Hi all,
> >
> > I wants to detect glitches in my video. Is there any filter to achieve
> it.?
>
> How does the glitch look like? It it's black, you could try the
> blackdetect or blackframe filters.
>
> Michael
>
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4159655569_314e17dcb7.jpg (278K) Download Attachment
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Re: Filter to detect video glitches

Carl Eugen Hoyos-2
2019-03-10 10:58 GMT+01:00, Venkateswaran.S <[hidden email]>:
> Please find the attached image for your reference.

Didn't the decoder return an error when decoding
attached image?

Please avoid top-posting here, Carl Eugen
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Re: Filter to detect video glitches

Carl Zwanzig
In reply to this post by Venkateswaran.S
(What have you already tried?)

On 3/10/2019 1:58 AM, Venkateswaran.S wrote:
> Glitches are video aftrifacts created by poor encoding/decoding or problem
> in network connection while playing online video. It can't be detected by
> blackdetector. Please find the attached image for your reference.

"glitch" can mean lots of things, and a decoding failure is only one of them
and better to call it what it is (i.e head-switching noise from an analog
source can also be called a glitch, as could a dropped frame).

In this case, it looks like a transmission/data error or dropped packet(s).
Can a frame-based filter even look for that? You're kind of getting into
Automatic Content Recognition, which gets tricky and isn't a job for the
command line utils.

There is a freezedetect filter, but that may not be what you want.

I think you better off looking at the log messages for decoder errors.

z!
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Re: Filter to detect video glitches

Venkateswaran.S
On Mon, Mar 11, 2019 at 1:00 AM Carl Zwanzig <[hidden email]> wrote:
(What have you already tried?)
As of now, I'm passing every decoded frame to OpenCV to perform some image
analysis (like dissimilarity between present and the past frame), but this
method doesn't work accurately and also time-consuming.

"glitch" can mean lots of things, and a decoding failure is only one of
> them
> and better to call it what it is (i.e head-switching noise from an analog
> source can also be called a glitch, as could a dropped frame).


Yes, it caused due to lots of things, but most of the time glitches occur
at a tiny part of the frame (macroblock).

In this case, it looks like a transmission/data error or dropped packet(s).
> Can a frame-based filter even look for that? You're kind of getting into
> Automatic Content Recognition, which gets tricky and isn't a job for the
> command line utils.
>

I'm using FFmpeg C API not the cmd util.

There is a freezedetect filter, but that may not be what you want.
>

it's only used to detect contiguous static frames.

I think you better off looking at the log messages for decoder errors.
>

how to dump log of decoder.?


> z!
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Re: Filter to detect video glitches

Carl Zwanzig
On 3/10/2019 6:09 PM, Venkateswaran.S wrote:
> I'm using FFmpeg C API not the cmd util.

The ffmpeg-users list is aimed at command-line users, you might try on the
libav-user mailing list, it covers the libraries themselves
(https://lists.ffmpeg.org/mailman/listinfo/libav-user/).


> how to dump log of decoder.?

If you're calling the decoder directly, the various routines involved will
all return a status. You may need to look into the behavior of the decoders
in how they deal with corrupt data and whether they silently reconstruct a
bad frame.

If you don't already have the ffmpeg source code, it would be a good idea to
download that and look at the routines directly.

z!
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Re: Filter to detect video glitches

Carl Zwanzig
In reply to this post by Venkateswaran.S

Just a follow-on badly-analyzed thought--

You might be able to get some useful info by looking at the frequency
distributions of a bad frame vs a good one. A frame with more detail would
generally have more/higher freq's. Depends on content, of course.

z!
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Re: Filter to detect video glitches

Kieran O Leary
In reply to this post by Venkateswaran.S
On Sun, 10 Mar 2019, 07:29 Venkateswaran.S, <[hidden email]>
wrote:

> Hi all,
>
> I wants to detect glitches in my video. Is there any filter to achieve it.?
>

Have you looked into the signalstats filter? It is often used in the
QCTools application in order to find glitches in digitised/migrated
analogue/digital videotapes.
It looks like your example image might have a spike in UV values and maybe
even a spike in saturation. It could be worth analysing a glitchy video in
QCTools,figuring out which stats seem to be triggered by the glitches you
encounter,then add the appropriate calls to your API usage. The qct-parse
python tool tries something somewhat similar
https://github.com/FutureDays/qct-parse/blob/master/README.md

Best,

Kieran.

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