Mailing List Archive

jak <nospam@please.ty> wrote:
> rbowman ha scritto:
> > On Sun, 9 Apr 2023 09:40:51 +0100, Chris Green wrote:
> >
> >> I'm looking for a Python (3) library to access (read only at present)
> >> the metadata in MP4 video files, in particular I want to get at dates
> >> and times.
> >>
> >> What's available to do this? Ideally something available in the Ubuntu
> >> repositories but I can install with PIP if necessary.
> >
> > https://mutagen.readthedocs.io/en/latest/
> >
>
> I thought it only dealt about audio.

That's why I hadn't thought it would help me as I'm after getting
metadata from an MP4 video file but I guess the metadata format may be
the same regardless of whether it's video or audio.

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Chris Green
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On Sun, 9 Apr 2023 20:19:37 +0100, Chris Green wrote:

> That's why I hadn't thought it would help me as I'm after getting
> metadata from an MP4 video file but I guess the metadata format may be
> the same regardless of whether it's video or audio.

If yuo chase back through the various ISOs you tend to wind up at Apple's
QuickTime container format as the parent. The compression methods for the
media etc will differ but at least the structure of the file is
documented. It's tedious but you can walk through the atoms (chunks,
blocks, boxes) and find the metadata.

There is the disclaimer

https://mutagen.readthedocs.io/en/latest/user/mp4.html

so it may not work for your intended purposes, particularly for modifying
the data. That gets tricky since it may change the size of the chunk.

https://pypi.org/project/tinytag/

is another one but it's only for reading the metadata.

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Chris Green ha scritto:
> jak <nospam@please.ty> wrote:
>> rbowman ha scritto:
>>> On Sun, 9 Apr 2023 09:40:51 +0100, Chris Green wrote:
>>>
>>>> I'm looking for a Python (3) library to access (read only at present)
>>>> the metadata in MP4 video files, in particular I want to get at dates
>>>> and times.
>>>>
>>>> What's available to do this? Ideally something available in the Ubuntu
>>>> repositories but I can install with PIP if necessary.
>>>
>>> https://mutagen.readthedocs.io/en/latest/
>>>
>>
>> I thought it only dealt about audio.
>
> That's why I hadn't thought it would help me as I'm after getting
> metadata from an MP4 video file but I guess the metadata format may be
> the same regardless of whether it's video or audio.
>

Easiest way I found was run ffprobe command via popen. It can output the
information you need in json format which is easily readable with the
json library.

command:
ffprobe -v warning -i "input.mp4" -show_streams -of json
python:
Popen(command, stderr=STDOUT, stdout=PIPE, encoding='utf8')
json:
json.loads(''.join(p.stdout.readlines()))

It's easy to find a version of ffmpeg/ffprobe for every platform.
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jak <nospam@please.ty> wrote:
> Chris Green ha scritto:
> > jak <nospam@please.ty> wrote:
> >> rbowman ha scritto:
> >>> On Sun, 9 Apr 2023 09:40:51 +0100, Chris Green wrote:
> >>>
> >>>> I'm looking for a Python (3) library to access (read only at present)
> >>>> the metadata in MP4 video files, in particular I want to get at dates
> >>>> and times.
> >>>>
> >>>> What's available to do this? Ideally something available in the Ubuntu
> >>>> repositories but I can install with PIP if necessary.
> >>>
> >>> https://mutagen.readthedocs.io/en/latest/
> >>>
> >>
> >> I thought it only dealt about audio.
> >
> > That's why I hadn't thought it would help me as I'm after getting
> > metadata from an MP4 video file but I guess the metadata format may be
> > the same regardless of whether it's video or audio.
> >
>
> Easiest way I found was run ffprobe command via popen. It can output the
> information you need in json format which is easily readable with the
> json library.
>
> command:
> ffprobe -v warning -i "input.mp4" -show_streams -of json
> python:
> Popen(command, stderr=STDOUT, stdout=PIPE, encoding='utf8')
> json:
> json.loads(''.join(p.stdout.readlines()))
>
> It's easy to find a version of ffmpeg/ffprobe for every platform.

Thank you, that worked straight away, ffprobe is installed on my
systems already and I can probably just grep for the tag I want as all
I'm looking for is the date of its creation which appears (twice) with
the tag "creation_time".

This is just to handle the occasional MP4 that a python program which
basically manages JPEGs can't handle. It throws an exception so I can
just get that to run a simple bash script to get the creation date.

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On 10Apr2023 13:10, Chris Green <cl@isbd.net> wrote:
>> command:
>> ffprobe -v warning -i "input.mp4" -show_streams -of json
>> python:
>> Popen(command, stderr=STDOUT, stdout=PIPE, encoding='utf8')
>> json:
>> json.loads(''.join(p.stdout.readlines()))
>>
>> It's easy to find a version of ffmpeg/ffprobe for every platform.
>
>Thank you, that worked straight away, ffprobe is installed on my
>systems already and I can probably just grep for the tag I want as all
>I'm looking for is the date of its creation which appears (twice) with
>the tag "creation_time".
>
>This is just to handle the occasional MP4 that a python program which
>basically manages JPEGs can't handle. It throws an exception so I can
>just get that to run a simple bash script to get the creation date.

Yes, ffprobe is great, particularly the JSON output mode, very parsable.

If you want to get into the knitty gritty you could try my `cs.iso14496`
package, which has a full MP4/MOV parser and a hook for getting the
metadata.

Not as convenient as ffprobe, but if you care about the innards...

Cheers,
Cameron Simpson <cs@cskk.id.au>
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