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

Toerless Eckert <eckert@cisco.com> Sun, 17 November 2013 17:58 UTC

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Date: Sun, 17 Nov 2013 09:56:48 -0800
From: Toerless Eckert <eckert@cisco.com>
To: Maik Merten <maikmerten@googlemail.com>
Message-ID: <20131117175648.GB11012@cisco.com>
References: <5284AB73.5030505@googlemail.com> <5285209D.7020407@googlemail.com> <CAGgHUiSROwRznKZWD4kjn8Vu7SrUVwOnHN1EJ-PTgR=WQmcxAQ@mail.gmail.com> <CAOJ7v-2najyMhcVNC8r0Sg+8xgkgDwasBSz476zA0BEpi2X5Pg@mail.gmail.com> <528559E4.3020903@nostrum.com> <5286272B.5000005@bbs.darktech.org> <CAOJ7v-3AT-5BHZAp2hvqm3Th20dk8Ec3orrj-voFMBwZroPdLA@mail.gmail.com> <DUB127-W49A2377699D81E3A1EA912E0FB0@phx.gbl> <CAOJ7v-27XiBGFT8=i=8ZyWYPP4UE64Jo41Pe_i1GAAUWfhDBuA@mail.gmail.com> <52877178.6040002@googlemail.com>
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Subject: Re: [rtcweb] H261/MPEG-1 video quality
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On Sat, Nov 16, 2013 at 02:22:00PM +0100, Maik Merten wrote:
> A major reason IMO why H.261 performs so badly (apart from the old 
> format design) is that nobody seems to have cared to transfer new 
> technology for determining smart encoding choices to that old format (it 
> just makes little commercial sense to strap rockets onto a pig if a 
> newer format such as H.263 or H.264 is available). It appears that 
> encoders for H.261 are mostly "1990ies" regarding encoding technology. 
> From today's point of view such encoders are blazingly fast, but better 
> quality could be achieved with encoders that spend some computation on 
> making smarter encoding choices.

Right. I think the logics of the market space would make a choice
of h261 as MTI just a big desaster and fruitless exercise
in retro-engineering.

- You start with legacy software, then it breaks under a lot
  more/different use than what it was written for in the 90th and you
  have to invest cycles fixing it.
- You wonder whether you should still optimize it, but ohh, wait,
  lets check IPR on any possible optimization, oh wait, if i need
  to start checking IPR, why the heck did i use this legacy codec.
- You try to figure how to make chips work whose native h261
  support if at all still existing still works. YOu wonder if/how
  the next generation of chips could do better on h261.

Toerless

> Maik
> 
> 
> Am 16.11.2013 03:18, schrieb Justin Uberti:
> >Thanks. Performance at 256 kbps is clearly unacceptable, 1933 kbps is
> >pretty decent. Would be great to see a 512 kbps and 1024 kbps version to
> >understand where things go from bad to good.
> >
> >
> >On Fri, Nov 15, 2013 at 3:42 PM, Hervé W. <h_o_w_@hotmail.com
> ><mailto:h_o_w_@hotmail.com>> wrote:
> >
> >    <http://ge.tt/2bp1Zrz><http://ge.tt/2bp1Zrz><http://ge.tt/2bp1Zrz>http://ge.tt/2bp1Zrz
> >
> >    options used:
> >    mencoder.exe -ovc lavc -lavcopts vcodec=h261:vbitrate=256 -o
> >    irene-256k.h261.avi sign_irene_cif.y4m
> >
> >    mencoder.exe -ovc lavc -lavcopts
> >    vcodec=h261:vbitrate=256:last_pred=3:predia=2:dia=2:precmp=2:cmp=2:subcmp=2:preme=2:mbd=0
> >    -o irene-256k.h261.miscoptions.avi sign_irene_cif.y4m
> >
> >    mencoder.exe -ovc lavc -lavcopts
> >    vcodec=h261:vbitrate=15999:last_pred=3:predia=2:dia=2:precmp=2:cmp=2:subcmp=2:preme=2:mbd=0
> >    -o irene-highbitrate.h261.avi sign_irene_cif.y4m
> >
> >    You can probably derive ffmpeg/avconv options from those.
> >
> >    Notes
> >
> >      * There's a ticket open about h261
> >        <https://trac.ffmpeg.org/ticket/3143>https://trac.ffmpeg.org/ticket/3143
> >      * 15999 kbps was not the bitrate irene-highbitrate ended up using;
> >        that was more like 1933 kbps
> >      * My untrained eye did not see any difference between
> >        irene-256k.h261.avi and irene-256k.h261.miscoptions.avi but
> >        maybe most of those options are (rightly) ignored for h261.
> >
> >
> >    - Hervé
> >
> >    ------------------------------------------------------------------------
> >    From: juberti@google.com <mailto:juberti@google.com>
> >    Date: Fri, 15 Nov 2013 14:00:50 -0800
> >    To: cowwoc@bbs.darktech.org <mailto:cowwoc@bbs.darktech.org>
> >    CC: rtcweb@ietf.org <mailto:rtcweb@ietf.org>
> >    Subject: Re: [rtcweb] H261/MPEG-1 video quality (was: I'd love it if
> >    patents evaporated)
> >
> >
> >     From what I understand, the clip from this thread was encoded using
> >    MPEG-1, not H.261. Aside from
> >    http://www-mobile.ecs.soton.ac.uk/peter/h261/, I don't think we have
> >    seen any samples of actual H.261 output that give a good indication
> >    of its suitability.
> >
> >
> >    On Fri, Nov 15, 2013 at 5:52 AM, cowwoc <cowwoc@bbs.darktech.org
> >    <mailto:cowwoc@bbs.darktech.org>> wrote:
> >
> >
> >        Excellent work Adam. I can't speak for others, but at 254 kbps
> >        (corrected figure from your follow-up post) H.261 is definitely
> >        "good enough" and better than an audio-only connection.
> >
> >        Gili
> >
> >
> >        On 14/11/2013 6:16 PM, Adam Roach wrote:
> >
> >            I sent a reply to this earlier, but just now realized that
> >            it went only to Justin, not to the list.
> >
> >
> >            On 11/14/13 13:59, Justin Uberti wrote:
> >
> >                Thanks, this is interesting. Is the ffmpeg 261 encoder
> >                limited to CIF/QCIF, or can you specify arbitrary sizes?
> >
> >
> >            It looks like the ffmpeg mpeg-1 coder works for arbitrary
> >            sizes. I'm not sure what the difference between mpeg-1 and
> >            H.261 are, though, so we could be talking apples and oranges
> >            (or at least apples and pears) here. I'll note that mpeg-1
> >            came out in 1991, which is a good 22 years in the past. I'm
> >            not drawing IPR conclusions for you, but invite you to
> >            ponder the implications yourself.
> >
> >            Following Maik's lead with the mpeg-1 js decoder, I put this
> >            together:
> >
> >            https://dl.dropboxusercontent.com/u/53717247/mpg/maven.html
> >
> >            ...with this commandline:
> >
> >               ffmpeg -i maven.mp4 -f mpeg1video -flags qprd -mbd rd
> >            -cmp rd -subcmp rd -mbcmp rd -precmp rd -trellis 2 -g 100
> >            -vb 256k maven.mpg
> >
> >            I don't really understand most of those options (I just
> >            cribbed them from Maik's example) or whether any of them
> >            would introduce more latency than is reasonable for a
> >            real-time conversation, but I will observe:
> >
> >             1. The encoder claims that it was performing on the order
> >                of 90 - 100 fps on my (admittedly modern) system;
> >             2. The resolution is 640x360 (somewhat larger than DCIF);
> >             3. The video is not, to my eye, unusable (draw your own
> >                conclusions, as it's clearly not as nice as modern codecs);
> >             4. At 74 seconds and 4.7 MBytes (i.e., 37.6 Mbits), this
> >                encoding works out to 508 kbits/second total.
> >
> >
> >
> >            Source video here, and NASA is acknowledged as the source of
> >            the material contained therein:
> >            http://www.youtube.com/watch?v=ijAO0FFExx0
> >
> >            /a
> >
> >
> >
> >            _______________________________________________
> >            rtcweb mailing list
> >            rtcweb@ietf.org  <mailto:rtcweb@ietf.org>
> >            https://www.ietf.org/mailman/listinfo/rtcweb
> >
> >
> >
> >        _______________________________________________
> >        rtcweb mailing list
> >        rtcweb@ietf.org <mailto:rtcweb@ietf.org>
> >        https://www.ietf.org/mailman/listinfo/rtcweb
> >
> >
> >
> >    _______________________________________________ rtcweb mailing list
> >    rtcweb@ietf.org <mailto:rtcweb@ietf.org>
> >    https://www.ietf.org/mailman/listinfo/rtcweb
> >
> >
> >
> >
> >_______________________________________________
> >rtcweb mailing list
> >rtcweb@ietf.org
> >https://www.ietf.org/mailman/listinfo/rtcweb
> >
> 
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-- 
---
Toerless Eckert, eckert@cisco.com
Cisco NSSTG Systems & Technology Architecture
SDN: Let me play with the network, mommy!