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On Tue, Jan 1, 2013 at 5:19 PM, Nuno J. Silva <nunojsilva@×××××××.pt> wrote: |
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> On 2013-01-01, Stroller wrote: |
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> |
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>> On 30 December 2012, at 11:39, Nuno J. Silva wrote: |
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>>> ... |
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>>> The AVI container has been used by windows for a long time, so I'd say |
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>>> chances are that it will work on more systems, but I can't say for sure. |
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>> |
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>> But h264 in an AVI is invalid. |
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>> |
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>> AVI is dated and just plain nasty. |
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>> |
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>> You should use something else (like h264 in an MP4) if you possibly can. |
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> |
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> AVI is old, AVI has issues. AVI is not compatible with some |
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> codecs. *But* AVI has been around for long enough to be supported by |
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> many versions of Windows and Office, and what we're looking for here is |
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> whatever offers the broadest support. I don't even think Windows (at |
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> least up to 7) has a builtin h264 decoder. At least I remember having to |
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> install codecs in Vista and 7 machines in order to view h264 Youtube |
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> videos. |
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Did a bit of googling. Windows 7 includes h264 support. |
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In any case, there's something *critically* important missing in most |
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of this discussion about AVI vs something else. |
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Just because Windows supports AVI doesn't mean that Windows includes |
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all possible codecs you might stuff in an AVI. There's h264, there's |
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MPEG, MPEG2, Theora, RLE Windows Media and hundreds of codecs I've |
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forgotten. And that's just video. For audio, there's more variation |
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than there is for WAV[1]. In addition to anything WAVE files might |
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contain, you might find just about anything. There's FLAC, AAC, Speex, |
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MP2a, MP3, Vorbis and thousands more. |
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AVI is just a container. Nothing more. Containers are like ZIP files |
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or tar files, but instead of containing a filesystem, they contain a |
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variable number of audio and video streams in such a way that the |
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audio and video data for a moment in time are close together and |
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easily accessible. The meat is in the audio and video streams, the |
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format of which we call codecs. |
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The big question is what *codecs* are available on the target systems. |
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If you're looking for the absolute widest degree of support, you're |
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looking at DIB encoding for video with uLaw PCM for audio. But that's |
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going to be a *huge* file, because there's no compression at all! |
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The best compression that's going to be available on the widest |
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variety of systems is probably going to be MPEG2 video with MPEG2 |
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layer 3 audio. |
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The best compression that might be available, period, would be h.264, |
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combined with MP4 audio, in an MP4 container. Almost as good results |
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can be had with h.264 video, MP4 audio in an AVI container.[2] |
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So, Francisco, what version of Windows will your slideshow be played on? |
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[1] Yeah, WAVE files aren't exactly simple, either. They can contain |
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different PCM encodings. There's aLaw, uLaw, float... |
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[2] For full effectiveness, h.264 requires features that the AVI |
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container doesn't have. |
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|
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-- |
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:wq |
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