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

Monty Montgomery <xiphmont@gmail.com> Fri, 15 November 2013 05:39 UTC

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References: <52855B35.3080605@nostrum.com> <CEAAB858.AA2AF%stewe@stewe.org> <CAGgHUiShX3wYpFCjUP9cK6isjQLMYDYcYCTbc=Ene9wHfaeNPQ@mail.gmail.com>
Date: Fri, 15 Nov 2013 00:39:07 -0500
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From: Monty Montgomery <xiphmont@gmail.com>
To: Leon Geyser <lgeyser@gmail.com>
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Subject: Re: [rtcweb] H261/MPEG-1 video quality
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Stephan just implied strongly they haven't, despite the 20 years.

And, BTW, I was serious when I mentioned Theora earlier as well.

Monty

On Fri, Nov 15, 2013 at 12:33 AM, Leon Geyser <lgeyser@gmail.com>; wrote:
> 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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>> https://www.ietf.org/mailman/listinfo/rtcweb
>>
>
>
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