Drop frames during framemd5 calculation of DPX files

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Drop frames during framemd5 calculation of DPX files

Matthew Yang
Hello there

I have been experiencing drop frames during calculation of framemd5
checksums for a bunch of DPX files.

The command:

*ffmpeg -start_number 86400 -i finalDPX_forDCP\Respire%08d.dpx -f framemd5
original_md5_2.txt*

The result:

frame=20837 fps=5.2 q=-0.0 Lsize=    1628kB time=00:14:28.20 bitrate=
 15.4kbits/s dup=0 *drop=867* speed=0.216x
video:1107194832kB audio:0kB subtitle:0kB other streams:0kB global
headers:0kB muxing overhead: unknown

I ran the checksum calculation twice and it has the same exact number of
drop frames.

The full results can be seen in the txt file attached.

Please kindly advise on how I can solve this problem as I am unable to
resolve it on my own.

Thank you!

Best
Matthew

Matthew Yang* | *Archive Officer
Asian Film Archive
100 Victoria Street, #06-01
Singapore 188064
*Tel:* +65 6957 8508 (Collections) / +65 6777 3243 (Main) | *Fax:* +65 6694
5264
*Website <https://www.asianfilmarchive.org/>* | *Facebook*
<https://www.facebook.com/asianfilmarchive/?ref=br_rs> | *Twitter*
<https://twitter.com/AFA_Archive> | *Instagram*
<https://www.instagram.com/asianfilmarchive/>

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framemd5_dropframes.txt (3K) Download Attachment
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Re: Drop frames during framemd5 calculation of DPX files

kumowoon1025
Hi,

> frame=20837 fps=5.2 q=-0.0 Lsize=    1628kB time=00:14:28.20 bitrate=
> 15.4kbits/s dup=0 *drop=867* speed=0.216x
> video:1107194832kB audio:0kB subtitle:0kB other streams:0kB global
> headers:0kB muxing overhead: unknown
867 frames dropped in 868 seconds, maybe ffmpeg has estimated 1 fps off? Try specifying 1 fps higher from what is detected explicitly at the input.

Regards,
Ted Park

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Re: Drop frames during framemd5 calculation of DPX files

Gyan Doshi-2
In reply to this post by Matthew Yang


On 26-03-2020 02:17 pm, Matthew Yang wrote:

> Hello there
>
> I have been experiencing drop frames during calculation of framemd5
> checksums for a bunch of DPX files.
>
> The command:
>
> *ffmpeg -start_number 86400 -i finalDPX_forDCP\Respire%08d.dpx -f framemd5
> original_md5_2.txt*
>
> The result:
>
> frame=20837 fps=5.2 q=-0.0 Lsize=    1628kB time=00:14:28.20 bitrate=
>   15.4kbits/s dup=0 *drop=867* speed=0.216x
> video:1107194832kB audio:0kB subtitle:0kB other streams:0kB global
> headers:0kB muxing overhead: unknown
>
> I ran the checksum calculation twice and it has the same exact number of
> drop frames.
>
> The full results can be seen in the txt file attached.
>
> Please kindly advise on how I can solve this problem as I am unable to
> resolve it on my own.

Some snafu with detected fps.

Use

     ffmpeg -start_number 86400 -i finalDPX_forDCP\Respire%08d.dpx -vsync 0 -f framemd5
allframes_md5.txt


Gyan

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Re: Drop frames during framemd5 calculation of DPX files

Matthew Yang
Hello all

Thank you all for the suggestions.

I tried: ffmpeg -start_number 86400 -i finalDPX_forDCP\Respire%08d.dpx
*-vsync* 0 -f framemd5
allframes_md5.txt

I still get a similar result without the stated drop frames. framemd5
checksum spits out 867 frames less than total frames.

Strange..

Matthew Yang* | *Archive Officer
Asian Film Archive
100 Victoria Street, #06-01
Singapore 188064
*Tel:* +65 6957 8508 (Collections) / +65 6777 3243 (Main) | *Fax:* +65 6694
5264
*Website <https://www.asianfilmarchive.org/>* | *Facebook*
<https://www.facebook.com/asianfilmarchive/?ref=br_rs> | *Twitter*
<https://twitter.com/AFA_Archive> | *Instagram*
<https://www.instagram.com/asianfilmarchive/>


On Thu, 26 Mar 2020 at 23:06, Gyan Doshi <[hidden email]> wrote:

>
>
> On 26-03-2020 02:17 pm, Matthew Yang wrote:
> > Hello there
> >
> > I have been experiencing drop frames during calculation of framemd5
> > checksums for a bunch of DPX files.
> >
> > The command:
> >
> > *ffmpeg -start_number 86400 -i finalDPX_forDCP\Respire%08d.dpx -f
> framemd5
> > original_md5_2.txt*
> >
> > The result:
> >
> > frame=20837 fps=5.2 q=-0.0 Lsize=    1628kB time=00:14:28.20 bitrate=
> >   15.4kbits/s dup=0 *drop=867* speed=0.216x
> > video:1107194832kB audio:0kB subtitle:0kB other streams:0kB global
> > headers:0kB muxing overhead: unknown
> >
> > I ran the checksum calculation twice and it has the same exact number of
> > drop frames.
> >
> > The full results can be seen in the txt file attached.
> >
> > Please kindly advise on how I can solve this problem as I am unable to
> > resolve it on my own.
>
> Some snafu with detected fps.
>
> Use
>
>      ffmpeg -start_number 86400 -i finalDPX_forDCP\Respire%08d.dpx -vsync
> 0 -f framemd5
> allframes_md5.txt
>
>
> Gyan
>
> _______________________________________________
> ffmpeg-user mailing list
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> https://ffmpeg.org/mailman/listinfo/ffmpeg-user
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> To unsubscribe, visit link above, or email
> [hidden email] with subject "unsubscribe".
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Re: Drop frames during framemd5 calculation of DPX files

kumowoon1025
Hi,

> I tried: ffmpeg -start_number 86400 -i finalDPX_forDCP\Respire%08d.dpx
> *-vsync* 0 -f framemd5
> allframes_md5.txt
>
> I still get a similar result without the stated drop frames. framemd5
> checksum spits out 867 frames less than total frames.

Shouldn’t that be vsync drop? Since the issue is the misdetected frame rate?

Regards,
Ted Park

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Re: Drop frames during framemd5 calculation of DPX files

Matthew Yang
Hello Ted

vsync drop worked well for me. can you explain what causes misdetected
frame rates?

Thanks.

Best
Matt
Matthew Yang* | *Archive Officer
Asian Film Archive
100 Victoria Street, #06-01
Singapore 188064
*Tel:* +65 6957 8508 (Collections) / +65 6777 3243 (Main) | *Fax:* +65 6694
5264
*Website <https://www.asianfilmarchive.org/>* | *Facebook*
<https://www.facebook.com/asianfilmarchive/?ref=br_rs> | *Twitter*
<https://twitter.com/AFA_Archive> | *Instagram*
<https://www.instagram.com/asianfilmarchive/>


On Tue, 31 Mar 2020 at 10:27, Ted Park <[hidden email]> wrote:

> Hi,
>
> > I tried: ffmpeg -start_number 86400 -i finalDPX_forDCP\Respire%08d.dpx
> > *-vsync* 0 -f framemd5
> > allframes_md5.txt
> >
> > I still get a similar result without the stated drop frames. framemd5
> > checksum spits out 867 frames less than total frames.
>
> Shouldn’t that be vsync drop? Since the issue is the misdetected frame
> rate?
>
> Regards,
> Ted Park
>
> _______________________________________________
> ffmpeg-user mailing list
> [hidden email]
> https://ffmpeg.org/mailman/listinfo/ffmpeg-user
>
> To unsubscribe, visit link above, or email
> [hidden email] with subject "unsubscribe".
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Re: Drop frames during framemd5 calculation of DPX files

Carl Eugen Hoyos-2


> Am 31.03.2020 um 08:19 schrieb Matthew Yang <[hidden email]>:
>
>
> vsync drop worked well for me.

> can you explain what causes misdetected
> frame rates?

The dpx files store a frame rate that is ignored by the demuxer (and therefore unused for the default output frame rate) but used to calculate timestamps on decoding, leading to frame drops.
(This is at least my working hypothesis.)
You should be able to force the correct framerate with the input option “-framerate”.

Please find out what top-posting means and avoid it here.

Carl Eugen
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Re: Drop frames during framemd5 calculation of DPX files

Erik Dobberkau
>
> > can you explain what causes misdetected frame rates?
>
> The dpx files store a frame rate that is ignored by the demuxer (and
> therefore unused for the default output frame rate) but used to calculate
> timestamps on decoding, leading to frame drops.
>
>
You mean it's drop-frame time code?
Sorry for the pun.
But a 23.976 (24000/1001) frame rate could be a sensible explanation.
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Re: Drop frames during framemd5 calculation of DPX files

kumowoon1025
In reply to this post by Carl Eugen Hoyos-2
Hi,

>> can you explain what causes misdetected
>> frame rates?
>
> The dpx files store a frame rate that is ignored by the demuxer (and therefore unused for the default output frame rate) but used to calculate timestamps on decoding, leading to frame drops.

I did not know that, why would it ignore the frame rate? Isn’t the framerate the film source original if it’s there?

Regards,
Ted Park

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Re: Drop frames during framemd5 calculation of DPX files

Carl Eugen Hoyos-2
Am Mi., 1. Apr. 2020 um 04:40 Uhr schrieb Ted Park <[hidden email]>:

> >> can you explain what causes misdetected
> >> frame rates?
> >
> > The dpx files store a frame rate that is ignored by the demuxer
> > (and therefore unused for the default output frame rate) but used
> > to calculate timestamps on decoding, leading to frame drops.
>
> I did not know that, why would it ignore the frame rate?

The image2 demuxer (that is used for dpx files) has never
heard of images with a framerate and therefore doesn't
try to read it.
Afaict, the dpx decoder uses the framerates.

> Isn’t the framerate the film source original if it’s there?

I don't know for sure but if you are talking about scans,
this simply doesn't matter.

Carl Eugen
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Re: Drop frames during framemd5 calculation of DPX files

kumowoon1025
Hi,

> The image2 demuxer (that is used for dpx files) has never
> heard of images with a framerate and therefore doesn't
> try to read it.
> Afaict, the dpx decoder uses the framerates.
I see… That would explain the weird 24 tbr 25 tbn 24 tbc, if I understand correctly?


>> Isn’t the framerate the film source original if it’s there?
>
> I don't know for sure but if you are talking about scans,
> this simply doesn't matter.

I was actually asking because I was wondering if there were any systems out there that save the scanned fps instead.

Regards,
Ted Park

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Re: Drop frames during framemd5 calculation of DPX files

Carl Eugen Hoyos-2
Am Fr., 3. Apr. 2020 um 00:00 Uhr schrieb Ted Park <[hidden email]>:

> > The image2 demuxer (that is used for dpx files) has never
> > heard of images with a framerate and therefore doesn't
> > try to read it.
> > Afaict, the dpx decoder uses the framerates.
> I see… That would explain the weird 24 tbr 25 tbn 24 tbc, if I
> understand correctly?

Yes.

Carl Eugen
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