Apple Video Foundation (AVF) and .mpg files

Richmond richmondmathewson at gmail.com
Tue Mar 26 18:37:51 EDT 2019


Looking at "Get Info" for the 2 movie files at the top of the page I 
referenced in my earlier message:

http://hubblesource.stsci.edu/sources/video/clips/details/images/centaur_1.mpg

http://hubblesource.stsci.edu/sources/video/clips/details/images/centaur_2.mpg

the two codecs are listed there.

So: the BIG question is where that sort of INFO is stored in a file and 
how LiveCode can access it and read it.

What is odd, in LiveCode 9.0.3 at least, is that if those 2 clips are 
imported into a stack neither the
Project Browser or the Application Overview will show a Property 
Inspector for either clip.

LiveCode 7.1.4 will open a proeprty inspector for both of these clips 
but offers no helpful information.

The $60,000 question has to be: can LiveCode read a file's metadata?

Richmonds-Mac-mini:~ richmond$ mdls 
/Users/richmond/Desktop/videoFormats/centaur_1.mpg
kMDItemCodecs                      = (
     "MPEG-1 Video"
)

Richmonds-Mac-mini:~ richmond$ mdls 
/Users/richmond/Desktop/videoFormats/centaur_2.mpg
kMDItemCodecs                      = (
     "MPEG-2 Video"
)

Richmond.

On 26.03.19 23:28, Paul Dupuis via use-livecode wrote:
> Richmond,
>
> I good suggestion. Thank you. However, looking at an identical video 
> clip encoded as MPEG-1 and as MPEG-2 in a test editor shows lots of 
> gibberish and no obvious text tags to tell the encoding.
>
> Unfortunately, I don't have time to research byte level binary 
> encoding differences between MPEG-1 and MPEG-2, which is why I was 
> hoping some LiveCode media guru had already done this and would share.
>
> It was a good idea to try though.
>
>
>
> On 3/26/2019 5:17 PM, Richmond via use-livecode wrote:
>> I suppose if you open an .mpg file as a TEXT file it should
>> contain standard markers as to whether it is encoded as MPEG-1 or 
>> MPEG-2.
>>
>> Useful samples here: http://hubblesource.stsci.edu/sources/video/clips/
>>
>> Richmond.
>>
>> On 26.03.19 22:32, Paul Dupuis via use-livecode wrote:
>>> Livecode 9.x.x uses Apple Video Foundation (AVF) for the LC Player 
>>> object under OSX.
>>> AVF supports MPEG-1 video but not MPEG-2 video.
>>> Both MPEG-1 and MPEG-2 use the .mpg file extenstion.
>>>
>>> Question for any media geniuses on this list: Is there a way in 
>>> LiveCode to tell a MPEG-1 .mpg file from a MPEG-2.mpg file?
>>>
>>>
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>>
>>
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>
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