22 Feb
2015
22 Feb
'15
3:36 p.m.
Hi Carl,
Re: Sound Sync.
I'm using 1.76 which I've just realised is not the latest.. in the
timing tab I changed frame rate from 25 to 24 and I believe DCP-o-Matic
used to say, audio re-sampled to xxx, but it does not now so I must be
changing the wrong value.
Any ideas? Thanks, Kevin.
22 Feb
22 Feb
3:44 p.m.
New subject: [DCP-o-matic] Sound Sync
Am 22.02.2015 um 16:36 schrieb Kevin Orman:
Hi Carl,
Re: Sound Sync.
I'm using 1.76 which I've just realised is not the latest.. in the timing tab I
changed frame rate from 25 to 24 and I believe DCP-o-Matic used to say, audio re-sampled
to xxx, but it does not now so I must be changing the wrong value.
Any ideas? Thanks, Kevin.
Hi Keith,
the timing tab is the wrong place to adjust the DCP frame rate in order to create a 24fps
DCP with proper audio resampling from a 25fps source.
You have to leave all fields the way they are there and select the intended frame rate
under the DCP tab. That will instruct DCP-o-matic to apply the proper resampling to the
audio.
So in this case, leave it at 25fps under Timing, and set to 24 fps in the DCP tab. You
will then see the comment on audio resampling applied under the content->audio tab.
We had a similiar issue just a few days ago on the list or on the forum. Maybe we need
some clarification for the frame rate field in the timing tab. It only designates source
frame rate reference and should only be changed manually when there is a wrong reference
on the source file.
- Carsten
4:45 p.m.
New subject: [DCP-o-matic] Sound Sync
On the same subject, I'm guessing that when DCP-o-matic resamples audio
it is performing a simple resampling and not a time-stretching
algorithm, and so the pitch of the audio will change.
This is normally fine, but in some cases e.g. with music videos it can
be undesirable.
There are various pieces of software that have a time-stretching
function (inc. the open source Audacity). Does anyone have a
recommendation for the best program to use for this, which produces
minimum audio distortion?
And am I right in assuming that DCP-o-matic doesn't do this anyway?
Many thanks,
Jim
On 22/02/2015 15:44, Carsten Kurz wrote:
Am 22.02.2015 um 16:36 schrieb Kevin Orman:
Hi Carl,
Re: Sound Sync.
I'm using 1.76 which I've just realised is not the latest.. in the timing tab I
changed frame rate from 25 to 24 and I believe DCP-o-Matic used to say, audio re-sampled
to xxx, but it does not now so I must be changing the wrong value.
Any ideas? Thanks, Kevin.
Hi Keith,
the timing tab is the wrong place to adjust the DCP frame rate in order to create a 24fps
DCP with proper audio resampling from a 25fps source.
You have to leave all fields the way they are there and select the intended frame rate
under the DCP tab. That will instruct DCP-o-matic to apply the proper resampling to the
audio.
So in this case, leave it at 25fps under Timing, and set to 24 fps in the DCP tab. You
will then see the comment on audio resampling applied under the content->audio tab.
We had a similiar issue just a few days ago on the list or on the forum. Maybe we need
some clarification for the frame rate field in the timing tab. It only designates source
frame rate reference and should only be changed manually when there is a wrong reference
on the source file.
- Carsten
_______________________________________________
DCPomatic mailing list
DCPomatic(a)carlh.net
http://main.carlh.net/cgi-bin/mailman/listinfo/dcpomatic
5:03 p.m.
New subject: [DCP-o-matic] Sound Sync
Am 22.02.2015 um 17:45 schrieb Jim Dummett:
There are various pieces of software that have a
time-stretching function (inc. the open source Audacity). Does anyone have a
recommendation for the best program to use for this, which produces minimum audio
distortion?
A while ago I sent this link to a fabulous sampling-rate-converter online comparison site
to Carl:
http://src.infinitewave.ca/
Pick your choice ;-) Seems Audacity is not so bad at all. Don't know which functions
Dcp-o-matic uses. The site references three different ffmpeg methods with very different
results.
- Carsten
8:16 p.m.
New subject: [DCP-o-matic] Sound Sync
On 22/02/2015 17:03, Carsten Kurz wrote:
A while ago I sent this link to a fabulous
sampling-rate-converter
online comparison site to Carl: http://src.infinitewave.ca/
This is really useful. But as far as I can see, this is for sample rate
conversion, rather than time-stretching. Difference is the
time-stretching preserves the original pitch of the sound which makes it
a much more complicated conversion and more prone to unpleasant
artefacts. Or I may have mis-understood what this site is for...
Carl: Thanks loads for clarifying what DCP-o-matic already does.
Jim
9:34 p.m.
New subject: [DCP-o-matic] Sound Sync
Am 22.02.2015 um 21:16 schrieb Jim Dummett:
This is really useful. But as far as I can see, this
is for sample rate conversion, rather than time-stretching. Difference is the
time-stretching preserves the original pitch of the sound which makes it a much more
complicated conversion and more prone to unpleasant artefacts. Or I may have
mis-understood what this site is for...
First of all - DCP-o-matic does not apply any time-compression/expansion currently.
Timecompression/expansion can use different algorithms. For musical applications,
phase-vocoders and more elaborate formant-preserving methods are state-of-the art.
But in this case of media conversions, we are talking about rather small changes - nobody
speeds up or slows down a video by 40% expecting to preserve video and audio timing and
tonality. For this type of media conversion, the simpler SRC/interpolation and filtering
algorithms are sufficient in my opinion, even for time-compression and -expansion.
- Carsten
9:20 p.m.
New subject: [DCP-o-matic] Sound Sync
On 22 Feb 2015, at 18:03, Carsten Kurz
<audiovisual(a)t-online.de> wrote:
A while ago I sent this link to a fabulous sampling-rate-converter online comparison site
to Carl:
http://src.infinitewave.ca/
Pick your choice ;-) Seems Audacity is not so bad at all. Don't know which functions
Dcp-o-matic uses. The site references three different ffmpeg methods with very different
results.
I always use iZotope’s SRC as built into the inexpensive “Sample Manager” app. Inaudible.
Cheers,
Andrew
5:09 p.m.
New subject: [DCP-o-matic] Sound Sync
It does basic resampling indeed, if there is no recent changes that I missed.
I strongly suggest to avoid changing 25 to 24. I'm happy using SMPTE
and never used Interop that is the only real need for 24 fps
conversion.
Manuel AC
On Sun, Feb 22, 2015 at 11:45 AM, Jim Dummett <j(a)dummett.org> wrote:
On the same subject, I'm guessing that when
DCP-o-matic resamples audio it
is performing a simple resampling and not a time-stretching algorithm, and
so the pitch of the audio will change.
This is normally fine, but in some cases e.g. with music videos it can be
undesirable.
There are various pieces of software that have a time-stretching function
(inc. the open source Audacity). Does anyone have a recommendation for the
best program to use for this, which produces minimum audio distortion?
And am I right in assuming that DCP-o-matic doesn't do this anyway?
Many thanks,
Jim
On 22/02/2015 15:44, Carsten Kurz wrote:
Am 22.02.2015 um 16:36 schrieb Kevin Orman:
_______________________________________________
DCPomatic mailing list
DCPomatic(a)carlh.net
http://main.carlh.net/cgi-bin/mailman/listinfo/dcpomatic Hi Carl,
Re: Sound Sync.
I'm using 1.76 which I've just realised is not the latest.. in the timing
tab I changed frame rate from 25 to 24 and I believe DCP-o-Matic used to
say, audio re-sampled to xxx, but it does not now so I must be changing the
wrong value.
Any ideas? Thanks, Kevin.
Hi Keith,
the timing tab is the wrong place to adjust the DCP frame rate in order to
create a 24fps DCP with proper audio resampling from a 25fps source.
You have to leave all fields the way they are there and select the
intended frame rate under the DCP tab. That will instruct DCP-o-matic to
apply the proper resampling to the audio.
So in this case, leave it at 25fps under Timing, and set to 24 fps in the
DCP tab. You will then see the comment on audio resampling applied under the
content->audio tab.
We had a similiar issue just a few days ago on the list or on the forum.
Maybe we need some clarification for the frame rate field in the timing tab.
It only designates source frame rate reference and should only be changed
manually when there is a wrong reference on the source file.
- Carsten
_______________________________________________
DCPomatic mailing list
DCPomatic(a)carlh.net
http://main.carlh.net/cgi-bin/mailman/listinfo/dcpomatic
6:47 p.m.
New subject: [DCP-o-matic] Sound Sync
Am 22.02.2015 um 18:09 schrieb Manuel AC:
It does basic resampling indeed, if there is no recent
changes that I missed.
I strongly suggest to avoid changing 25 to 24. I'm happy using SMPTE
and never used Interop that is the only real need for 24 fps
conversion.
Even 25fps Interop now works with 'most' servers. We recently had a major
documentary release in germany in the form of a 25fps Interop. Seems it didn't cause
too much trouble. I created 25fps Interop DCPs with DCP-o-matic for our Sony without a
problem. But an older 25fps Interop created with an early version of DCP-o-matic or
DVD-o-matic did not play.
Some devices, like the Dolby DSS100/DSP100 can not play 25fps content - but in this case,
not in SMPTE, not in Interop.
- Carsten
5:52 p.m.
New subject: [DCP-o-matic] Sound Sync
On Sun, 22 Feb 2015, Jim Dummett wrote:
On the same subject, I'm guessing that when
DCP-o-matic resamples audio it is
performing a simple resampling and not a time-stretching algorithm, and so the
pitch of the audio will change.
Correct. It uses FFmpeg's "swr" resampler.
This is normally fine, but in some cases e.g. with
music videos it can be
undesirable.
There are various pieces of software that have a time-stretching function
(inc. the open source Audacity). Does anyone have a recommendation for the
best program to use for this, which produces minimum audio distortion?
And am I right in assuming that DCP-o-matic doesn't do this anyway?
Correct again. DCP-o-matic does not currently do time-stretching.
Best regards,
Carl
Many thanks,
Jim
On 22/02/2015 15:44, Carsten Kurz wrote:
Am 22.02.2015 um 16:36 schrieb Kevin Orman:
_______________________________________________
DCPomatic mailing list
DCPomatic(a)carlh.net
http://main.carlh.net/cgi-bin/mailman/listinfo/dcpomatic
Hi Carl,
Re: Sound Sync.
I'm using 1.76 which I've just realised is not the latest.. in the timing
tab I changed frame rate from 25 to 24 and I believe DCP-o-Matic used to
say, audio re-sampled to xxx, but it does not now so I must be changing
the wrong value.
Any ideas? Thanks, Kevin.
Hi Keith,
the timing tab is the wrong place to adjust the DCP frame rate in order to
create a 24fps DCP with proper audio resampling from a 25fps source.
You have to leave all fields the way they are there and select the intended
frame rate under the DCP tab. That will instruct DCP-o-matic to apply the
proper resampling to the audio.
So in this case, leave it at 25fps under Timing, and set to 24 fps in the
DCP tab. You will then see the comment on audio resampling applied under the
content->audio tab.
We had a similiar issue just a few days ago on the list or on the forum.
Maybe we need some clarification for the frame rate field in the timing tab.
It only designates source frame rate reference and should only be changed
manually when there is a wrong reference on the source file.
- Carsten
_______________________________________________
DCPomatic mailing list
DCPomatic(a)carlh.net
http://main.carlh.net/cgi-bin/mailman/listinfo/dcpomatic
5:52 p.m.
New subject: [DCP-o-matic] Sound Sync
We had a similiar issue just a few days ago on the
list or on the forum.
Maybe we need some clarification for the frame rate field in the timing
tab. It only designates source frame rate reference and should only be
changed manually when there is a wrong reference on the source file.
I've just added a warning under that field (to DCP-o-matic git).
Regards,
Carl
3718
days inactive
3718
days old
10 comments
6 participants
participants (6)
-
Andrew Levine -
Carl Hetherington -
Carsten Kurz -
Jim Dummett -
Kevin Orman -
Manuel AC