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using ffmpeg command line with python's subprocess module

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  using ffmpeg command line with python's subprocess module iMath <redstone-cold@163.com> - 2013-12-02 03:34 -0800
    Re: using ffmpeg command line with python's subprocess module Chris Angelico <rosuav@gmail.com> - 2013-12-02 22:40 +1100
    Re: using ffmpeg command line with python's subprocess module Ben Finney <ben+python@benfinney.id.au> - 2013-12-03 08:19 +1100
      Re: using ffmpeg command line with python's subprocess module iMath <redstone-cold@163.com> - 2013-12-02 17:15 -0800
        Re: using ffmpeg command line with python's subprocess module rusi <rustompmody@gmail.com> - 2013-12-02 17:42 -0800
          Re: using ffmpeg command line with python's subprocess module iMath <redstone-cold@163.com> - 2013-12-03 17:42 -0800
          Re: using ffmpeg command line with python's subprocess module iMath <redstone-cold@163.com> - 2013-12-03 17:42 -0800
            Re: using ffmpeg command line with python's subprocess module Andreas Perstinger <andipersti@gmail.com> - 2013-12-04 10:38 +0100
              Re: using ffmpeg command line with python's subprocess module iMath <redstone-cold@163.com> - 2013-12-05 22:23 -0800
                Re: using ffmpeg command line with python's subprocess module Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-06 09:23 +0000
                  Re: using ffmpeg command line with python's subprocess module iMath <redstone-cold@163.com> - 2013-12-06 06:52 -0800
                    Re: using ffmpeg command line with python's subprocess module Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-06 15:12 +0000
                      Re: using ffmpeg command line with python's subprocess module rusi <rustompmody@gmail.com> - 2013-12-06 07:15 -0800
                    Re: using ffmpeg command line with python's subprocess module rusi <rustompmody@gmail.com> - 2013-12-06 07:13 -0800
                    Re: using ffmpeg command line with python's subprocess module Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-12-06 15:34 +0000
                      Re: using ffmpeg command line with python's subprocess module Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-06 15:53 +0000
                        Re: using ffmpeg command line with python's subprocess module rusi <rustompmody@gmail.com> - 2013-12-06 08:19 -0800
                          Re: using ffmpeg command line with python's subprocess module Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-06 16:25 +0000
                            Re: using ffmpeg command line with python's subprocess module rusi <rustompmody@gmail.com> - 2013-12-06 08:45 -0800
                      Re: using ffmpeg command line with python's subprocess module MRAB <python@mrabarnett.plus.com> - 2013-12-06 16:41 +0000
                        Re: using ffmpeg command line with python's subprocess module rusi <rustompmody@gmail.com> - 2013-12-06 08:53 -0800
                          Re: using ffmpeg command line with python's subprocess module Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2013-12-07 13:01 +1300
                Re: using ffmpeg command line with python's subprocess module Ned Batchelder <ned@nedbatchelder.com> - 2013-12-06 06:31 -0500
            Re: using ffmpeg command line with python's subprocess module Chris Angelico <rosuav@gmail.com> - 2013-12-04 21:51 +1100
              Re: using ffmpeg command line with python's subprocess module iMath <redstone-cold@163.com> - 2013-12-06 06:54 -0800
                Re: using ffmpeg command line with python's subprocess module Chris Angelico <rosuav@gmail.com> - 2013-12-07 01:59 +1100
                  Re: using ffmpeg command line with python's subprocess module iMath <redstone-cold@163.com> - 2013-12-09 01:04 -0800
                    Re: using ffmpeg command line with python's subprocess module Andreas Perstinger <andipersti@gmail.com> - 2013-12-10 13:59 +0100
      Re: using ffmpeg command line with python's subprocess module Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2013-12-03 10:33 +0100
        Re: using ffmpeg command line with python's subprocess module iMath <redstone-cold@163.com> - 2013-12-03 05:59 -0800
    Re: using ffmpeg command line with python's subprocess module Chris Angelico <rosuav@gmail.com> - 2013-12-03 08:25 +1100

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#60858 — using ffmpeg command line with python's subprocess module

I have few wav files that I can use either of the following command line mentioned here
https://trac.ffmpeg.org/wiki/How%20to%20concatenate%20%28join,%20merge%29%20media%20files
 to concatenate


ffmpeg -f concat -i <(for f in ./*.wav; do echo "file '$f'"; done) -c copy output.wav
ffmpeg -f concat -i <(printf "file '%s'\n" ./*.wav) -c copy output.wav
ffmpeg -f concat -i <(find . -name '*.wav' -printf "file '%p'\n") -c copy output.wav


anyone know how to convert either of them to work with python's subprocess module, it would be better if your solution is platform independent .

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#60860

On Mon, Dec 2, 2013 at 10:34 PM, iMath <redstone-cold@163.com> wrote:
> I have few wav files that I can use either of the following command line mentioned here
> https://trac.ffmpeg.org/wiki/How%20to%20concatenate%20%28join,%20merge%29%20media%20files
>  to concatenate
>
>
> ffmpeg -f concat -i <(for f in ./*.wav; do echo "file '$f'"; done) -c copy output.wav
> ffmpeg -f concat -i <(printf "file '%s'\n" ./*.wav) -c copy output.wav
> ffmpeg -f concat -i <(find . -name '*.wav' -printf "file '%p'\n") -c copy output.wav

In bash, the <(...) notation is like piping: it executes the command
inside the parentheses and uses that as standard input to ffmpeg. So
if you work out what the commands are doing (it looks like they emit a
line saying "file '...'" for each .wav file in the current directory,
possibly including subdirectories) and replicate that in Python, you
should be able to make it cross-platform.

ChrisA

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#60885

Chris Angelico <rosuav@gmail.com> writes:

> On Mon, Dec 2, 2013 at 10:34 PM, iMath <redstone-cold@163.com> wrote:
> > ffmpeg -f concat -i <(for f in ./*.wav; do echo "file '$f'"; done) -c copy output.wav
> > ffmpeg -f concat -i <(printf "file '%s'\n" ./*.wav) -c copy output.wav
> > ffmpeg -f concat -i <(find . -name '*.wav' -printf "file '%p'\n") -c copy output.wav
>
> In bash, the <(...) notation is like piping: it executes the command
> inside the parentheses and uses that as standard input to ffmpeg.

Not standard input, no. What it does is create a temporary file to
contain the result, and inserts that file name on the command line. This
is good for programs that require an actual file, not standard input.

So the above usage seems right to me: the ‘ffmpeg -i FOO’ option is
provided with a filename dynamically created by Bash, referring to a
temporary file that contains the output of the subshell.

-- 
 \     “Welchen Teil von ‘Gestalt’ verstehen Sie nicht?  [What part of |
  `\                ‘gestalt’ don't you understand?]” —Karsten M. Self |
_o__)                                                                  |
Ben Finney

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#60903

在 2013年12月3日星期二UTC+8上午5时19分21秒，Ben Finney写道：
> Chris Angelico <rosuav@gmail.com> writes:
> 
> 
> 
> > On Mon, Dec 2, 2013 at 10:34 PM, iMath <redstone-cold@163.com> wrote:
> 
> > > ffmpeg -f concat -i <(for f in ./*.wav; do echo "file '$f'"; done) -c copy output.wav
> 
> > > ffmpeg -f concat -i <(printf "file '%s'\n" ./*.wav) -c copy output.wav
> 
> > > ffmpeg -f concat -i <(find . -name '*.wav' -printf "file '%p'\n") -c copy output.wav
> 
> >
> 
> > In bash, the <(...) notation is like piping: it executes the command
> 
> > inside the parentheses and uses that as standard input to ffmpeg.
> 
> 
> 
> Not standard input, no. What it does is create a temporary file to
> 
> contain the result, and inserts that file name on the command line. This
> 
> is good for programs that require an actual file, not standard input.
> 
> 
> 
> So the above usage seems right to me: the ‘ffmpeg -i FOO’ option is
> 
> provided with a filename dynamically created by Bash, referring to a
> 
> temporary file that contains the output of the subshell.
> 
> 
> 
> -- 
> 
>  \     “Welchen Teil von ‘Gestalt’ verstehen Sie nicht?  [What part of |
> 
>   `\                ‘gestalt’ don't you understand?]” —Karsten M. Self |
> 
> _o__)                                                                  |
> 
> Ben Finney

so is there any way to create a temporary file by Python here ?

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#60907

On Tuesday, December 3, 2013 6:45:42 AM UTC+5:30, iMath wrote:
> so is there any way to create a temporary file by Python here ?

http://docs.python.org/2/library/tempfile.html

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#60985

在 2013年12月3日星期二UTC+8上午9时42分11秒，rusi写道：
> On Tuesday, December 3, 2013 6:45:42 AM UTC+5:30, iMath wrote:
> 
> > so is there any way to create a temporary file by Python here ?
> 
> 
> 
> http://docs.python.org/2/library/tempfile.html
I use the following code to do the test ,but error occurred ,it prompts system cannot find specified files ,but the files are indeed exists there ,any help ?

with tempfile.TemporaryFile() as fp:
    fp.write(("file '"+'a1.mp3'+"'\n").encode('utf-8'))
    fp.write(("file '"+'a2.mp3'+"'\n").encode('utf-8'))

    subprocess.call(['ffmpeg/ffmpeg', '-f', 'concat','-i',fp, '-c',  'copy', 'a3.mp3'])

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#60986

在 2013年12月3日星期二UTC+8上午9时42分11秒，rusi写道：
> On Tuesday, December 3, 2013 6:45:42 AM UTC+5:30, iMath wrote:
> 
> > so is there any way to create a temporary file by Python here ?
> 
> 
> 
> http://docs.python.org/2/library/tempfile.html
I use the following code to do the test ,but error occurred ,it prompts system cannot find specified files ,but the files are indeed exists there ,any help ?

with tempfile.TemporaryFile() as fp:
    fp.write(("file '"+'a1.mp3'+"'\n").encode('utf-8'))
    fp.write(("file '"+'a2.mp3'+"'\n").encode('utf-8'))

    subprocess.call(['ffmpeg/ffmpeg', '-f', 'concat','-i',fp, '-c',  'copy', 'a3.mp3'])

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#61001

iMath <redstone-cold@163.com> wrote:
>I use the following code to do the test ,but error occurred ,it
>prompts system cannot find specified files ,but the files are indeed
>exists there ,any help ?
>
>with tempfile.TemporaryFile() as fp:
>    fp.write(("file '"+'a1.mp3'+"'\n").encode('utf-8'))
>    fp.write(("file '"+'a2.mp3'+"'\n").encode('utf-8'))
>
>    subprocess.call(['ffmpeg/ffmpeg', '-f', 'concat','-i',fp, '-c',
> 'copy', 'a3.mp3'])

Basic rule: Always copy'n'paste the exact traceback you get.

I don't think you are running the code you have posted because your
subprocess call doesn't work:

>>> import tempfile, subprocess
>>> with tempfile.TemporaryFile() as fp:
...   subprocess.call(["foo", "bar", fp, "baz"])
... 
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "/usr/lib/python3.3/subprocess.py", line 520, in call
    with Popen(*popenargs, **kwargs) as p:
  File "/usr/lib/python3.3/subprocess.py", line 820, in __init__
    restore_signals, start_new_session)
  File "/usr/lib/python3.3/subprocess.py", line 1380, in _execute_child
    restore_signals, start_new_session, preexec_fn)
TypeError: Can't convert '_io.BufferedRandom' object to str implicitly

"fp" is a file object, but subprocess expects a list of strings as
its first argument.

Bye, Andreas

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#61114

在 2013年12月4日星期三UTC+8下午5时38分27秒，Andreas Perstinger写道：
> iMath <redstone-cold@163.com> wrote:
> 
> >I use the following code to do the test ,but error occurred ,it
> 
> >prompts system cannot find specified files ,but the files are indeed
> 
> >exists there ,any help ?
> 
> >
> 
> >with tempfile.TemporaryFile() as fp:
> 
> >    fp.write(("file '"+'a1.mp3'+"'\n").encode('utf-8'))
> 
> >    fp.write(("file '"+'a2.mp3'+"'\n").encode('utf-8'))
> 
> >
> 
> >    subprocess.call(['ffmpeg/ffmpeg', '-f', 'concat','-i',fp, '-c',
> 
> > 'copy', 'a3.mp3'])
> 
> 
> 
> Basic rule: Always copy'n'paste the exact traceback you get.
> 
> 
> 
> I don't think you are running the code you have posted because your
> 
> subprocess call doesn't work:
> 
> 
> 
> >>> import tempfile, subprocess
> 
> >>> with tempfile.TemporaryFile() as fp:
> 
> ...   subprocess.call(["foo", "bar", fp, "baz"])
> 
> ... 
> 
> Traceback (most recent call last):
> 
>   File "<stdin>", line 2, in <module>
> 
>   File "/usr/lib/python3.3/subprocess.py", line 520, in call
> 
>     with Popen(*popenargs, **kwargs) as p:
> 
>   File "/usr/lib/python3.3/subprocess.py", line 820, in __init__
> 
>     restore_signals, start_new_session)
> 
>   File "/usr/lib/python3.3/subprocess.py", line 1380, in _execute_child
> 
>     restore_signals, start_new_session, preexec_fn)
> 
> TypeError: Can't convert '_io.BufferedRandom' object to str implicitly
> 
> 
> 
> "fp" is a file object, but subprocess expects a list of strings as
> 
> its first argument.
> 
> 
> 
> Bye, Andreas
sorry for my fuss.
it prompts 
StdErr: -c: No such file or directory

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#61128

On 06/12/2013 06:23, iMath wrote:

Dearest iMath, wouldst thou be kind enough to partake of obtaining some 
type of email client that dost not sendeth double spaced data into this 
most illustrious of mailing lists/newsgroups.  Thanking thee for thine 
participation in my most humble of requests.  I do remain your most 
obedient servant.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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#61153

在 2013年12月6日星期五UTC+8下午5时23分59秒，Mark Lawrence写道：
> On 06/12/2013 06:23, iMath wrote:
> 
> 
> 
> Dearest iMath, wouldst thou be kind enough to partake of obtaining some 
> 
> type of email client that dost not sendeth double spaced data into this 
> 
> most illustrious of mailing lists/newsgroups.  Thanking thee for thine 
> 
> participation in my most humble of requests.  I do remain your most 
> 
> obedient servant.
> 
> 
> 
> -- 
> 
> My fellow Pythonistas, ask not what our language can do for you, ask 
> 
> what you can do for our language.
> 
> 
> 
> Mark Lawrence

yes ,I am a native Chinese speaker.I always post question by Google Group not through  email ,is there something wrong with it ?
your english is a little strange to me .

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#61156

On 06/12/2013 14:52, iMath wrote:
> 在 2013年12月6日星期五UTC+8下午5时23分59秒，Mark Lawrence写道：
>> On 06/12/2013 06:23, iMath wrote:
>>
>>
>>
>> Dearest iMath, wouldst thou be kind enough to partake of obtaining some
>>
>> type of email client that dost not sendeth double spaced data into this
>>
>> most illustrious of mailing lists/newsgroups.  Thanking thee for thine
>>
>> participation in my most humble of requests.  I do remain your most
>>
>> obedient servant.
>>
>>
>>
>> --
>>
>> My fellow Pythonistas, ask not what our language can do for you, ask
>>
>> what you can do for our language.
>>
>>
>>
>> Mark Lawrence
>
> yes ,I am a native Chinese speaker.I always post question by Google Group not through  email ,is there something wrong with it ?
> your english is a little strange to me .
>

You can see the extra lines inserted by google groups above.  It's not 
too bad in one and only one message, but when a message has been 
backwards and forwards several times it's extremely irritating, or worse 
still effectively unreadable.  Work arounds have been posted on this 
list, but I'd recommend using any decent email client.

The English I used was archaic, please ignore it :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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#61158

On Friday, December 6, 2013 8:42:02 PM UTC+5:30, Mark Lawrence wrote:
> The English I used was archaic, please ignore it :)

"Archaic" is almost archaic
"Old" is ever-young

:D

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#61157

On Friday, December 6, 2013 8:22:48 PM UTC+5:30, iMath wrote:
> 在 2013年12月6日星期五UTC+8下午5时23分59秒，Mark Lawrence写道：
> > On 06/12/2013 06:23, iMath wrote:
> > Dearest iMath, wouldst thou be kind enough to partake of obtaining some 
> > type of email client that dost not sendeth double spaced data into this 
> > most illustrious of mailing lists/newsgroups.  Thanking thee for thine 
> > participation in my most humble of requests.  I do remain your most 
> > obedient servant.

> yes ,I am a native Chinese speaker.I always post question by Google Group not through  email ,is there something wrong with it ?

Yes but its easily correctable

I recently answered this question to another poster here

https://groups.google.com/forum/#!searchin/comp.lang.python/rusi$20google$20groups|sort:date/comp.lang.python/C51hEvi-KbY/KSeaMFoHtcIJ

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#61159

On Fri, 06 Dec 2013 06:52:48 -0800, iMath wrote:

> yes ,I am a native Chinese speaker.I always post question by Google
> Group not through  email ,is there something wrong with it ? your
> english is a little strange to me .

Mark is writing in fake old-English style, the way people think English 
was spoken a thousand years ago. I don't know why he did that. Perhaps he 
thought it was amusing.

There are many problems with Google Groups. If you pay attention to this 
forum, you will see dozens of posts about "Managing Google Groups 
headaches" and other complaints:

- Google Groups double-spaces replies, so text which should appear like:

    line one
    line two
    line three
    line four

  turns into:

    line one
    blank line
    line two
    blank line
    line three
    blank line
    line four

- Google Groups often starts sending HTML code instead of plain text

- it often mangles indentation, which is terrible for Python code

- sometimes it automatically sets the reply address for posts to go
  to Google Groups, instead of the mailing list it should go to

- almost all of the spam on his forum comes from Google Groups, so many 
  people automatically filter everything from Google Groups straight to
  the trash.

There are alternatives to Google Groups:

- the mailing list, python-list@python.org

- Usenet, comp.lang.python

- the Gmane mirror:

  http://gmane.org/find.php?list=python-list%40python.org


and possibly others. You will maximise the number of people reading your 
posts if you avoid Google Groups. If for some reason you cannot use any 
of the alternatives, please take the time to fix some of the problems 
with Google Groups. If you search the archives, you should find some 
posts by Rusi defending Google Groups and explaining what he does to make 
it more presentable, and (if I remember correctly) I think Mark also 
sometimes posts a link to managing Google Groups.



-- 
Steven

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#61161

On 06/12/2013 15:34, Steven D'Aprano wrote:
(if I remember correctly) I think Mark also
> sometimes posts a link to managing Google Groups.
>

You do, and here it is https://wiki.python.org/moin/GoogleGroupsPython

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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#61162

On Friday, December 6, 2013 9:23:47 PM UTC+5:30, Mark Lawrence wrote:
> On 06/12/2013 15:34, Steven D'Aprano wrote:
> 
> (if I remember correctly) I think Mark also
> 
> > sometimes posts a link to managing Google Groups.
> 
> >
> 
> You do, and here it is https://wiki.python.org/moin/GoogleGroupsPython

That link needs updating.

Even if my almost-automatic correction methods are not considered
kosher for some reason or other, the thing that needs to go in there
is that GG has TWO problems

1. Blank lines
2. Long lines

That link only describes 1.

Roy's yesterday's post in "Packaging a proprietary python library"
says:

> I, and Rusi, know enough, and take the effort, to overcome its
> shortcomings doesn't change that.

But in fact his post takes care of 1 not 2.

In all fairness I did not know that 2 is a problem until rurpy pointed
it out recently and was not correcting it. In fact, I'd take the
trouble to make the lines long assuming that clients were intelligent
enough to fit it properly into whatever was the current window!!!

So someone please update that page!

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#61163

On 06/12/2013 16:19, rusi wrote:
> On Friday, December 6, 2013 9:23:47 PM UTC+5:30, Mark Lawrence wrote:
>> On 06/12/2013 15:34, Steven D'Aprano wrote:
>>
>> (if I remember correctly) I think Mark also
>>
>>> sometimes posts a link to managing Google Groups.
>>
>>>
>>
>> You do, and here it is https://wiki.python.org/moin/GoogleGroupsPython
>
> That link needs updating.
>
> Even if my almost-automatic correction methods are not considered
> kosher for some reason or other, the thing that needs to go in there
> is that GG has TWO problems
>
> 1. Blank lines
> 2. Long lines
>
> That link only describes 1.
>
> Roy's yesterday's post in "Packaging a proprietary python library"
> says:
>
>> I, and Rusi, know enough, and take the effort, to overcome its
>> shortcomings doesn't change that.
>
> But in fact his post takes care of 1 not 2.
>
> In all fairness I did not know that 2 is a problem until rurpy pointed
> it out recently and was not correcting it. In fact, I'd take the
> trouble to make the lines long assuming that clients were intelligent
> enough to fit it properly into whatever was the current window!!!
>
> So someone please update that page!
>

This is a community so why don't you?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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#61168

On Friday, December 6, 2013 9:55:54 PM UTC+5:30, Mark Lawrence wrote:
> On 06/12/2013 16:19, rusi wrote:

> > So someone please update that page!

> This is a community so why don't you?

Ok done (at least a first draft)
I was under the impression that anyone could not edit

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#61166

On 06/12/2013 15:34, Steven D'Aprano wrote:
> On Fri, 06 Dec 2013 06:52:48 -0800, iMath wrote:
>
>> yes ,I am a native Chinese speaker.I always post question by Google
>> Group not through  email ,is there something wrong with it ? your
>> english is a little strange to me .
>
> Mark is writing in fake old-English style, the way people think English
> was spoken a thousand years ago. I don't know why he did that. Perhaps he
> thought it was amusing.
>
[snip]
You're exaggerating. It's more like 500 years ago. :-)

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