Re: [rtcweb] H261/MPEG-1 video quality

Leon Geyser <lgeyser@gmail.com> Fri, 15 November 2013 05:33 UTC

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References: <52855B35.3080605@nostrum.com> <CEAAB858.AA2AF%stewe@stewe.org>
Date: Fri, 15 Nov 2013 07:33:42 +0200
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From: Leon Geyser <lgeyser@gmail.com>
To: "rtcweb@ietf.org" <rtcweb@ietf.org>
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Subject: Re: [rtcweb] H261/MPEG-1 video quality
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Hi everyone,
Maybe MPEG-1 Part 2 would be a better alternative to H.261. How can we
figure out if all the patents have expired for MPEG-1 Part 2?


On 15 November 2013 03:37, Stephan Wenger <stewe@stewe.org> wrote:

>  Folks,
> Please don’t consider H.261 and MPEG-1 part 2 as being in the same league
> in terms of coding efficiency or network friendliness.  They clearly are
> not.
> H.261 is what many call the first generation video coding standard.
>  MPEG-1 (and MPEG-2) are second generation.
> MPEG-1 has half-pel motion compensation.  H.261 has not.
> MPEG-1 has B frames.  H.261 has not.
> MPEG-1 has (arbitrary sized) slices that can be used for MTU size matching
> (although they are not commonly used for that purpose).  H.261 has not.
>  Instead, H.261 has the Group Of Block picture segmentation mechanism, that
> is clearly more optimized for parallel processing than for MTU size
> matching.
> MPEG-1 allows for significantly larger motion vectors (necessitated by B
> frames and the resulting longer prediction interval, but can be used even
> in P frame only coding).
> MPEG-1 has arbitrary picture sizes.  H.261 allows QCIF, CIF, and 4CIF (in
> “still image” mode, designed for low frame rate application; could run at
> high frame rate though).
> H.261 was ratified (in its first version) in 1988, and in the for all
> practical purposes final version in 1989.  Most people believe that all
> related patents have expired.
> MPEG-1 was ratified in late 1992.  Its “bug fix” successor MPEG-2 (which
> adds interlace support) was ratified less than a year later.  There are at
> least two major disputes going on today regarding technology allegedly
> infringed by a compliant implementation of MPEG-2.  Based on my technical
> understanding, one of these technologies is not in any way related to
> interlaced.
> Draw your own conclusions.
> Regards,
> Stephan
>
>
>
>
>   From: Adam Roach <adam@nostrum.com>
> Date: Thursday, 14 November, 2013 at 15:22
> To: "rtcweb@ietf.org" <rtcweb@ietf.org>
> Subject: Re: [rtcweb] H261/MPEG-1 video quality
>
>   On 11/14/13 17:16, Adam Roach wrote:
>
> At 74 seconds and 4.7 MBytes (i.e., 37.6 Mbits), this encoding works out
> to 508 kbits/second total.
>
>
> Whoops, I messed up my math. It's 148 seconds long, not 74 (Quicktime
> seems to divide it by two for some reason, although the javascript decode
> does the right thing). This works out to 254 kbps.
>
> /a
>
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