m4v e avi

[samael86]

ciao a tutti... dunque volevo sapere (spero nn sia una domanda fatta e rifatta) se gli mp4 (xke alla fine m4v son questo giusto?) sono degli avi.... se io prendo un file m4v e cambio l'estensione in avi..... posso??? è curiosità nn ho motivi o altro per farlo...

[ShadowMan]

Originariamente inviato da samael86

ciao a tutti... dunque volevo sapere (spero nn sia una domanda fatta e rifatta) se gli mp4 (xke alla fine m4v son questo giusto?) sono degli avi.... se io prendo un file m4v e cambio l'estensione in avi..... posso??? è curiosità nn ho motivi o altro per farlo...

Ma se hanno estensioni diverse perché dovrebbero essere la stessa cosa? mbe:

.MP4 versus .M4A file extensions

The existence of two different file extensions for naming audio-only MP4 files has been a source of confusion among users and multimedia playback software. Since MPEG-4 Part 14 is a container format, MPEG-4 files may contain any number of audio, video, and even subtitle streams, making it impossible to determine the type of streams in an MPEG-4 file based on its filename extension alone. In response, Apple Inc. started using and popularizing the .m4a file extension. Software capable of audio/video playback should recognize files with either .m4a or .mp4 file extensions, as would be expected, as there are no file format differences between the two. Most software capable of creating MPEG-4 audio will allow the user to choose the filename extension of the created MPEG-4 files.

While the only official file extension defined by the standard is .mp4, various file extensions are commonly used to indicate intended content:

* MPEG-4 files with audio and video generally use the standard .mp4 extension.
* Audio-only MPEG-4 files generally have a .m4a extension. This is especially true of non-protected content.
o MPEG-4 files with audio streams encrypted by FairPlay Digital Rights Management as sold through the iTunes Store use the .m4p extension. iTunes Plus tracks are unencrypted and use .m4a accordingly.
o Audio book and podcast files, which also contain metadata including chapter markers, images, and hyperlinks, can use the extension .m4a, but more commonly use the .m4b extension. An .m4a audio file cannot "bookmark" (remember the last listening spot), whereas .m4b extension files can.
o The Apple iPhone uses MPEG-4 audio for its ringtones but uses the .m4r extension rather than the .m4a extension.
* Raw MPEG-4 Visual bitstreams are named .m4v but this extension is also sometimes used for video in MP4 container format.[16]
* Mobile phones use 3GP, an implementation of MPEG-4 Part 12 (a.k.a MPEG-4/JPEG2000 ISO Base Media file format), similar to MP4. It uses .3gp and .3g2 extensions. These files also store non-MPEG-4 data (H.263, AMR, TX3G).

The common but non-standard use of the extensions .m4a and .m4v is due to the popularity of Apple’s iPod, iPhone, and iTunes Store. With modification, Nintendo's DSi and Sony's PSP can also play M4A.

Detto questo, i mp4 ed avi sono due contenitori differenti.
L'estensione la puoi modificare, ma sarà solo una modifica "estetica" perché non penso proprio che il file verrà riconosciuto correttamente.