Re: [FFmpeg-user] Reading or writing audio from audio device on MacOS

[Michael Glenn Williams]

Hey DopeLabs

Thank you for this. It makes sense for input and yes we are using loopback
and audio hijack.
So we *do* need a way to write to audio devices as well on Mac. We are
pulling the audio off of the video and want to send it into the local audio
routing system.


On Sat, May 9, 2020 at 8:31 AM DopeLabs  wrote:

>
>
> > On May 9, 2020, at 7:21 14AM, Michael Glenn Williams <
> michael.glenn.willi...@smartblondeco.com> wrote:
> >
> > Hi All,
> >
> > Is it possible to ask ffmpeg to read or write from/to an audio device on
> > MacOS? For example read from the microphone or playback to headphones?
>
> yes, you can use avfoundation. to get a list of input devices use the
> following command
>
> ffmpeg -f avfoundation -list_devices true -i ""
>
> that will provide you with a list of video and audio input devices...
>
> input devices are specified by the ID number separated by a colon provided
> in the previous command.
>
> you specify the devices as -i "videoid:audioid"
>
> here is an example of what mine looks like:
>
> [AVFoundation indev @ 0x7fc3d1703980] AVFoundation video devices:
> [AVFoundation indev @ 0x7fc3d1703980] [0] CamTwist
> [AVFoundation indev @ 0x7fc3d1703980] [1] FaceTime HD Camera (Built-in)
> [AVFoundation indev @ 0x7fc3d1703980] [2] webcamoid
> [AVFoundation indev @ 0x7fc3d1703980] [3] CamTwist (2VUY)
> [AVFoundation indev @ 0x7fc3d1703980] [4] EpocCam
> [AVFoundation indev @ 0x7fc3d1703980] [5] Capture screen 0
> [AVFoundation indev @ 0x7fc3d1703980] [6] Capture screen 1
> [AVFoundation indev @ 0x7fc3d1703980] [7] Capture screen 2
> [AVFoundation indev @ 0x7fc3d1703980] AVFoundation audio devices:
> [AVFoundation indev @ 0x7fc3d1703980] [0] Scarlett 18i20 USB
> [AVFoundation indev @ 0x7fc3d1703980] [1] Built-in Microphone
> [AVFoundation indev @ 0x7fc3d1703980] [2] EpocCam Microphone
> [AVFoundation indev @ 0x7fc3d1703980] [3] aux1
>
>
> for example if i want to do a screen capture of screen 1 for the video and
> the built in mic for the audio, the command would look like this
>
> ffmpeg -f avfoundation -i "6:1"
>
> if i only want audio
>
> ffmpeg -f avfoundation -i ":1"
>
> im pretty sure that avfoundation is strictly input devices only... that
> being said, you could probably pipe it to ffplay if you wanted to monitor
> local playback, in which it would use the system configured output device.
>
> there are other 3rd party tools you can use to route specific application
> audio output such as loopback or audiohijack.
>
> cheers =]
>
> >
> > Thank you!
> >
> > --
> >  Michael Williams
> >
> > CEO | CTO
> >
> > Smart Blonde Experiential
> > 8054991994
> > michael.glenn.willi...@smartblondeco.com
> > totalvu.tv
> > 13900 Marquesas Way, Marina Del Rey, CA
> > 
> > [image: facebook]
> >  [image:
> > twitter]  [image: linkedin]
> > 
> > ___
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-- 
 Michael Williams

CEO | CTO

Smart Blonde Experiential
8054991994
michael.glenn.willi...@smartblondeco.com
totalvu.tv
13900 Marquesas Way, Marina Del Rey, CA

[image: facebook]
 [image:
twitter]  [image: linkedin]

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Re: [FFmpeg-user] Decklink output latency, high

[Martin]

Hi!

Reducing the probesize removed basically all the delay, did not now that
the probesize had that impact. Big thank you for the tip!

 With the default probesize you could see a freeze frame of the first
decoded frame for a couple of secs, if I lower teh size it will start
decoding instantly. I compared to OBS SRT input and I'm now able to go
lower then the default input. Setting the probesize to low causes the SRT
input to trigger error/warning unable to store incoming packets so got to
try to find the best option for the probesizde for my needs without
triggering any errors. Latency is well within in my needs now.

The output is bursting a warning  from the SRT library in my compile, so
its a bit hard to get anything from the output, maybe a bit
uniniteresting now that I was presented with a working solution.

To sum things up, reducing the probesize removes the long delay I was
experiencing from the input stream on the decklink output.

Thanks again!

Regards Martin


Den lör 9 maj 2020 kl 21:33 skrev Carl Zwanzig :

> On 5/9/2020 12:21 PM, Marton Balint wrote:
> > 1) The most significant is probably input probing.
>
> I suspect the decklink part is a red herring, playback from a file to the
> decklink shoudl have almost no latency, certainly not 3+ seconds (doing a
> gdi screen capture to decklink is under 1 second latency).
>
> How long does it take for the stream to start playing with any other tool?
> Is the delay comparable?
>
> It would be helpful if you posted the complete command output. (Linux or
> windows?)
>
> z!
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Re: [FFmpeg-user] Decklink output latency, high

[Carl Zwanzig]

On 5/9/2020 12:21 PM, Marton Balint wrote:
1) The most significant is probably input probing. 


I suspect the decklink part is a red herring, playback from a file to the 
decklink shoudl have almost no latency, certainly not 3+ seconds (doing a 
gdi screen capture to decklink is under 1 second latency).


How long does it take for the stream to start playing with any other tool? 
Is the delay comparable?


It would be helpful if you posted the complete command output. (Linux or 
windows?)


z!
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Re: [FFmpeg-user] Decklink output latency, high

[Marton Balint]

On Sat, 9 May 2020, Martin wrote:


Hi!

Anybody have an idea why I get a couple of seconds of latency when
outputting to a decklink device? I

ffmpeg -fflags nobuffer -i srt://x   -f decklink -pix_fmt uyvy422 -c:a
pcm_s16le -ar 48000 -ac 2  "UltraStudio SDI"

Input is a TS stream SRT or UDP, input type does not r matter. Im getting
almost 4 seconds of delay on the SDI output compared to the stream. Seems a
bit high? One would expect a couple of frames. I have seen this question on
a few places but never seen an answer or solution.

Decklink driver 10.11.4, Windows

I only see this behaviour in ffmpeg not in other programs that uses
decklink output, Premiere, OBS etc.


Latency comes from multiple sources:

1) The most significant is probably input probing. You can limit this with 
-probesize and -analyzeduration.


2) decklink preroll - you can set this with -preroll, but a very low value 
will cause choppy output.


3) other buffering - I am sure there are other places :)

By setting 1) and 2) you can probably can reduce the latency, but I'd 
think it will still be higher than special purpose software.


Regards,
Marton
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[FFmpeg-user] Decklink output latency, high

[Martin]

Hi!

Anybody have an idea why I get a couple of seconds of latency when
outputting to a decklink device? I

ffmpeg -fflags nobuffer -i srt://x   -f decklink -pix_fmt uyvy422 -c:a
pcm_s16le -ar 48000 -ac 2  "UltraStudio SDI"

Input is a TS stream SRT or UDP, input type does not r matter. Im getting
almost 4 seconds of delay on the SDI output compared to the stream. Seems a
bit high? One would expect a couple of frames. I have seen this question on
a few places but never seen an answer or solution.

Decklink driver 10.11.4, Windows

I only see this behaviour in ffmpeg not in other programs that uses
decklink output, Premiere, OBS etc.

Regards Martain
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Re: [FFmpeg-user] Captured Audio Stream and Video Streams from YouTube Live are out of Sync

[Jim Ruxton]

Thanks Carl,



Am 09.05.2020 um 09:14 schrieb Jim Ruxton :

I am trying to retrieve a YoutubeLive stream and send the video stream to a 
video loopback device and the audio to my souncard. This works however it 
appears that the audio is delayed by a second or so. Is there a better way to 
do this so they aren't out of sync or failing that is there a way to set a 
delay on the video stream to compensate? Below is my command. I am using the 
Sky News You Tube Live as a test signal. I am on Ubuntu 19.10 .

ffmpeg -re -i $(youtube-dl -g -f 96 
https://www.youtube.com/watch?v=9Auq9mYxFEE)  -f v4l2 /dev/video2 -f alsa 
default

There is no synchronisation taking place between two outputs, if the delay is 
really constant between runs (I am not convinced it is), you can try the delay 
filters.

You are correct I now see that the delay is not consistent.


ffmpeg does not completely support your use case, it should work with ffplay.


Are you saying I could use ffplay in a similar way to split the audio 
and video from the stream but keep them in sync?



Jim

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Re: [FFmpeg-user] Reading or writing audio from audio device on MacOS

[DopeLabs]

> On May 9, 2020, at 7:21 14AM, Michael Glenn Williams 
>  wrote:
> 
> Hi All,
> 
> Is it possible to ask ffmpeg to read or write from/to an audio device on
> MacOS? For example read from the microphone or playback to headphones?

yes, you can use avfoundation. to get a list of input devices use the following 
command

ffmpeg -f avfoundation -list_devices true -i ""

that will provide you with a list of video and audio input devices...

input devices are specified by the ID number separated by a colon provided in 
the previous command.

you specify the devices as -i "videoid:audioid"

here is an example of what mine looks like:

[AVFoundation indev @ 0x7fc3d1703980] AVFoundation video devices:
[AVFoundation indev @ 0x7fc3d1703980] [0] CamTwist
[AVFoundation indev @ 0x7fc3d1703980] [1] FaceTime HD Camera (Built-in)
[AVFoundation indev @ 0x7fc3d1703980] [2] webcamoid
[AVFoundation indev @ 0x7fc3d1703980] [3] CamTwist (2VUY)
[AVFoundation indev @ 0x7fc3d1703980] [4] EpocCam
[AVFoundation indev @ 0x7fc3d1703980] [5] Capture screen 0
[AVFoundation indev @ 0x7fc3d1703980] [6] Capture screen 1
[AVFoundation indev @ 0x7fc3d1703980] [7] Capture screen 2
[AVFoundation indev @ 0x7fc3d1703980] AVFoundation audio devices:
[AVFoundation indev @ 0x7fc3d1703980] [0] Scarlett 18i20 USB
[AVFoundation indev @ 0x7fc3d1703980] [1] Built-in Microphone
[AVFoundation indev @ 0x7fc3d1703980] [2] EpocCam Microphone
[AVFoundation indev @ 0x7fc3d1703980] [3] aux1 


for example if i want to do a screen capture of screen 1 for the video and the 
built in mic for the audio, the command would look like this

ffmpeg -f avfoundation -i "6:1"

if i only want audio

ffmpeg -f avfoundation -i ":1"

im pretty sure that avfoundation is strictly input devices only... that being 
said, you could probably pipe it to ffplay if you wanted to monitor local 
playback, in which it would use the system configured output device.

there are other 3rd party tools you can use to route specific application audio 
output such as loopback or audiohijack.

cheers =]

> 
> Thank you!
> 
> -- 
>  Michael Williams
> 
> CEO | CTO
> 
> Smart Blonde Experiential
> 8054991994
> michael.glenn.willi...@smartblondeco.com
> totalvu.tv
> 13900 Marquesas Way, Marina Del Rey, CA
> 
> [image: facebook]
>  [image:
> twitter]  [image: linkedin]
> 
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Re: [FFmpeg-user] AviSynth Deinterlacers Comparison.png

[Mark Filipak]

On 05/09/2020 10:01 AM, Francois Visagie wrote:

From: ffmpeg-user [mailto:ffmpeg-user-boun...@ffmpeg.org] On Behalf Of
Carl Eugen Hoyos

Am 08.05.2020 um 18:51 schrieb Mark Filipak

Look at the attachment. I made it from this:
https://web.archive.org/web/20080501082420/http://heptium.sh.cvut.cz:8
0/~integra/deint/


The following is a little more relevant but both posts are from a time when
the good de-interlacers were unable to work in real-time on real hardware.
Since this is not true anymore, the value of the posts is very limited.
https://guru.multimedia.cx/deinterlacing-filters/comment-page-1/


@Mark, fully agreed with Carl Eugen's point.

It's unclear whether your interest in Avisynth extends beyond merely comparing 
against some other tool, but if it does you should be looking at more modern 
AVS deinterlacers from the time of QTGMC 
(https://forum.doom9.org/showthread.php?t=174544) and onward.


I'm not interested in Avisynth, Francois. I'm interested in motion compensation and, as seen in the 
picture I attached to my thread-starter, there used to be some that supposedly worked. I seek their 
equivalents in ffmpeg. I've not found an MC filter that works well.


Regards,
Mark.
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[FFmpeg-user] Stream scripting in Windows

[Mark Filipak]

Hi All,

ffprobe IN 2> FOO & TYPE FOO | FINDSTR /L "pcm_bluray"
reports "Stream #0:2[0x1101]: Audio: pcm_bluray"
(Note "Stream #0:2".)

ffmpeg -i IN -map 0 -c:v copy -c:a copy -c:0:2 pcm_s16be -sn -dn OUT
fails with "[matroska @ 0225ac037040] Invalid stream specifier: 0:2"

ffmpeg -i IN -map 0 -c:v copy -c:a copy -c:a:1 pcm_s16be -sn -dn OUT
succeeds of course.

Is there a workaround that will allow me to use "0:2" in a script? The alternative is a massive & 
incredibly-difficult-to-write parsing routine.


Thanks, Good Health,
Mark.
--
COVID-19 perspective (May 8, 2020):
The U.S. is 4% of world population, 33% of cases, 28% of deaths, accelerating.
The U.S. & S.Korea reported 1st cases on the same day, 22 Jan 2020.
In March, week 2, S.Korea (pop: 52 million) did 10,000 tests/day, 4 hour 
results.
In March, week 2, the U.S. (pop: 328 million) did 400 tests/day, 7 day results.
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[FFmpeg-user] Reading or writing audio from audio device on MacOS

[Michael Glenn Williams]

Hi All,

Is it possible to ask ffmpeg to read or write from/to an audio device on
MacOS? For example read from the microphone or playback to headphones?

Thank you!

-- 
 Michael Williams

CEO | CTO

Smart Blonde Experiential
8054991994
michael.glenn.willi...@smartblondeco.com
totalvu.tv
13900 Marquesas Way, Marina Del Rey, CA

[image: facebook]
 [image:
twitter]  [image: linkedin]

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Re: [FFmpeg-user] AviSynth Deinterlacers Comparison.png

[Francois Visagie]

> -Original Message-
> From: ffmpeg-user [mailto:ffmpeg-user-boun...@ffmpeg.org] On Behalf Of
> Carl Eugen Hoyos
> Sent: 09 May 2020 08:12
> To: FFmpeg user questions
> Subject: Re: [FFmpeg-user] AviSynth Deinterlacers Comparison.png
> 
> 
> 
> > Am 08.05.2020 um 18:51 schrieb Mark Filipak
> :
> >
> >
> > Look at the attachment. I made it from this:
> > https://web.archive.org/web/20080501082420/http://heptium.sh.cvut.cz:8
> > 0/~integra/deint/
> 
> The following is a little more relevant but both posts are from a time when
> the good de-interlacers were unable to work in real-time on real hardware.
> Since this is not true anymore, the value of the posts is very limited.
> https://guru.multimedia.cx/deinterlacing-filters/comment-page-1/

@Mark, fully agreed with Carl Eugen's point.

It's unclear whether your interest in Avisynth extends beyond merely comparing 
against some other tool, but if it does you should be looking at more modern 
AVS deinterlacers from the time of QTGMC 
(https://forum.doom9.org/showthread.php?t=174544) and onward.

> 
> Carl Eugen
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Re: [FFmpeg-user] Captured Audio Stream and Video Streams from YouTube Live are out of Sync

[Carl Eugen Hoyos]

> Am 09.05.2020 um 09:14 schrieb Jim Ruxton :
> 
> I am trying to retrieve a YoutubeLive stream and send the video stream to a 
> video loopback device and the audio to my souncard. This works however it 
> appears that the audio is delayed by a second or so. Is there a better way to 
> do this so they aren't out of sync or failing that is there a way to set a 
> delay on the video stream to compensate? Below is my command. I am using the 
> Sky News You Tube Live as a test signal. I am on Ubuntu 19.10 .
> 
> ffmpeg -re -i $(youtube-dl -g -f 96 
> https://www.youtube.com/watch?v=9Auq9mYxFEE)  -f v4l2 /dev/video2 -f alsa 
> default

There is no synchronisation taking place between two outputs, if the delay is 
really constant between runs (I am not convinced it is), you can try the delay 
filters.

ffmpeg does not completely support your use case, it should work with ffplay.

Carl Eugen
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Re: [FFmpeg-user] Captured Audio Stream and Video Streams from YouTube Live are out of Sync

[Stephan Monecke]

Have a look at the "-itsoffset" parameter for constant delays.
Also you might want to drop the "-re" [1].

[1] https://trac.ffmpeg.org/wiki/StreamingGuide#The-reflag
Best regards,
Stephan Monecke
-- 
Sent from my mobile device. Please excuse my brevity.

Am 9. Mai 2020 09:14:23 MESZ schrieb Jim Ruxton :
>I am trying to retrieve a YoutubeLive stream and send the video stream 
>to a video loopback device and the audio to my souncard. This works 
>however it appears that the audio is delayed by a second or so. Is
>there 
>a better way to do this so they aren't out of sync or failing that is 
>there a way to set a delay on the video stream to compensate? Below is 
>my command. I am using the Sky News You Tube Live as a test signal. I
>am 
>on Ubuntu 19.10 .
>
>ffmpeg -re -i $(youtube-dl -g -f 96 
>https://www.youtube.com/watch?v=9Auq9mYxFEE)  -f v4l2 /dev/video2 -f 
>alsa default
>
>Thanks,
>
>Jim
>
>
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[FFmpeg-user] Captured Audio Stream and Video Streams from YouTube Live are out of Sync

[Jim Ruxton]

I am trying to retrieve a YoutubeLive stream and send the video stream 
to a video loopback device and the audio to my souncard. This works 
however it appears that the audio is delayed by a second or so. Is there 
a better way to do this so they aren't out of sync or failing that is 
there a way to set a delay on the video stream to compensate? Below is 
my command. I am using the Sky News You Tube Live as a test signal. I am 
on Ubuntu 19.10 .


ffmpeg -re -i $(youtube-dl -g -f 96 
https://www.youtube.com/watch?v=9Auq9mYxFEE)  -f v4l2 /dev/video2 -f 
alsa default


Thanks,

Jim


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Re: [FFmpeg-user] AviSynth Deinterlacers Comparison.png

[Carl Eugen Hoyos]

> Am 08.05.2020 um 18:51 schrieb Mark Filipak 
> :
> 
> 
> Look at the attachment. I made it from this:
> https://web.archive.org/web/20080501082420/http://heptium.sh.cvut.cz:80/~integra/deint/

The following is a little more relevant but both posts are from a time when the 
good de-interlacers were unable to work in real-time on real hardware. Since 
this is not true anymore, the value of the posts is very limited.
https://guru.multimedia.cx/deinterlacing-filters/comment-page-1/

Carl Eugen
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Re: [FFmpeg-user] how to switch between transcoding and copy dynamicaly

[Carl Eugen Hoyos]

> Am 09.05.2020 um 04:13 schrieb qw :
> 
> 
> As I know, ffmpeg can do transcoding or copy for media file. how to switch 
> between transcoding and copy dynamicaly?

Only by writing your own application.

Carl Eugen
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