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by giantrobot
2014 days ago
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First of all, MPEG-4 Part 2 was an evolution of the h.263 spec. While all the h.26x have commonalities but they don't all have a linear relationship. Their commonalities are in high level concepts, not necessarily implementations. As I said and thought I made clear, MPEG-1/2 were unsuitable for streaming on consumer hardware of the era. The lowest practical bitrates for either was far higher than common dial-up rates. Neither spec supported Sub-QCIF frame sizes or frame rates below 15fps. Similarly audio was a problem as the specs wanted to use MPEG audio which likewise did not have super low bitrate modes. A software decoder could handle such things but the content was outside of a spec so you'd need the encoder and decoder to work hand in hand to work reliably. No one decided to develop h.263 and MPEG-4 just for funsies because MPEG-1/2 handled everything with aplomb. Low bitrate/high latency conditions (dial-up, cellular) were not well served by MPEG-1/2. |
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You did make it clear, you're just 100% incorrect. You can encode MPEG-1 video with any resolution and any bitrate you choose, just like MPEG-4 ASP. It is entirely within spec.
https://en.wikipedia.org/wiki/MPEG-1#Resolution/bitrate
> MPEG-4 Part 2 was an evolution of the h.263 spec
Not really. MPEG-4 ASP has much more in common with MPEG-2. MPEG-4 ASP for example omitted the in-loop deblocking in h.263, which reappeared in AVC/H.264.
> audio was a problem as the specs wanted to use MPEG audio which likewise did not have super low bitrate modes.
This is entirely wrong again. The MPEG-2 standard had defined audio modes down to 8kbits and 16000Hz.
https://en.wikipedia.org/wiki/MPEG-1#MPEG-2_audio_extensions
> No one decided to develop h.263 and MPEG-4 just for funsies
h.263 was developed for very low latency encoding to support real-time video conferencing better than MPEG-1/2.
MPEG-4 SP was an attempt to develop a patent royalty-free codec, which MPEG-1/2 were not (they are, now). MPEG-4 part-2 video does offer some small improvements in quality over MPEG-1/2 (qpel, 4mv), but nothing dramatic. That was saved for AVC, which is of course a significant improvement over MPEG-1/2 at low bitrates.