On Tue, Jan 1, 2013 at 5:19 PM, Nuno J. Silva <nunojsilva@ist.utl.pt> wrote:
> On 2013-01-01, Stroller wrote:
>
>> On 30 December 2012, at 11:39, Nuno J. Silva wrote:
>>> ...
>>> The AVI container has been used by windows for a long time, so I'd say
>>> chances are that it will work on more systems, but I can't say for sure.
>>
>> But h264 in an AVI is invalid.
>>
>> AVI is dated and just plain nasty.
>>
>> You should use something else (like h264 in an MP4) if you possibly can.
>
> AVI is old, AVI has issues. AVI is not compatible with some
> codecs. *But* AVI has been around for long enough to be supported by
> many versions of Windows and Office, and what we're looking for here is
> whatever offers the broadest support. I don't even think Windows (at
> least up to 7) has a builtin h264 decoder. At least I remember having to
> install codecs in Vista and 7 machines in order to view h264 Youtube
> videos.

Did a bit of googling. Windows 7 includes h264 support.

In any case, there's something *critically* important missing in most
of this discussion about AVI vs something else.

Just because Windows supports AVI doesn't mean that Windows includes
all possible codecs you might stuff in an AVI. There's h264, there's
MPEG, MPEG2, Theora, RLE Windows Media and hundreds of codecs I've
forgotten. And that's just video. For audio, there's more variation
than there is for WAV[1]. In addition to anything WAVE files might
contain, you might find just about anything. There's FLAC, AAC, Speex,
MP2a, MP3, Vorbis and thousands more.

AVI is just a container. Nothing more. Containers are like ZIP files
or tar files, but instead of containing a filesystem, they contain a
variable number of audio and video streams in such a way that the
audio and video data for a moment in time are close together and
easily accessible. The meat is in the audio and video streams, the
format of which we call codecs.

The big question is what *codecs* are available on the target systems.

If you're looking for the absolute widest degree of support, you're
looking at DIB encoding for video with uLaw PCM for audio. But that's
going to be a *huge* file, because there's no compression at all!

The best compression that's going to be available on the widest
variety of systems is probably going to be MPEG2 video with MPEG2
layer 3 audio.

The best compression that might be available, period, would be h.264,
combined with MP4 audio, in an MP4 container. Almost as good results
can be had with h.264 video, MP4 audio in an AVI container.[2]

So, Francisco, what version of Windows will your slideshow be played on?

[1] Yeah, WAVE files aren't exactly simple, either. They can contain
different PCM encodings. There's aLaw, uLaw, float...
[2] For full effectiveness, h.264 requires features that the AVI
container doesn't have.

--
:wq