Re: [rtcweb] H261/MPEG-1 video quality (was: I'd love it if patents evaporated)

Maik Merten <> Thu, 14 November 2013 19:12 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id CA8A711E8133 for <>; Thu, 14 Nov 2013 11:12:41 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.999
X-Spam-Status: No, score=-1.999 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, J_CHICKENPOX_45=0.6]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id 7wEwF9NBbe66 for <>; Thu, 14 Nov 2013 11:12:41 -0800 (PST)
Received: from ( [IPv6:2a00:1450:4008:c01::229]) by (Postfix) with ESMTP id C9B9111E80FA for <>; Thu, 14 Nov 2013 11:12:40 -0800 (PST)
Received: by with SMTP id v15so1289724bkz.0 for <>; Thu, 14 Nov 2013 11:12:34 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20120113; h=message-id:date:from:user-agent:mime-version:to:subject:references :in-reply-to:content-type:content-transfer-encoding; bh=ammfCUowo5U2AYLwGrVKjDzpYtdb1foJ/adPpMyMwrU=; b=B93W50Z74ClJBKeHS/NTLVTYAB6N63qh+PDpsdqs+/jxKs6sNc+WNDcyed5B7JGj/A QSRM+YvbURkuCnCSf0DVRasxYEYNdu9oAiTTIlI73rQxhiigzgfnNqFadR5ah2sWgSuL Tl1dp4lB5xCHHy+ttWIIoSGprow3S3ELySv14h8ijBl5PuaIoVJrww3+UjjsI5QTtQ9P hXB2v4QsFYx6QpVLAtW/38aw8EPasFHE50GZQ9HaWQbua2kWP+Erdh0oJi5Lh9VGAAVP 9ke1kefChPF6GdOVF1xxWpurYRgnoeyAlftCRZ/irQOjqPWi8R7ZG5Htk2vtZtLuENuo SodA==
X-Received: by with SMTP id sx12mr600713bkb.49.1384456354392; Thu, 14 Nov 2013 11:12:34 -0800 (PST)
Received: from [] ( []) by with ESMTPSA id pk7sm4451819bkb.2.2013. for <> (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 14 Nov 2013 11:12:33 -0800 (PST)
Message-ID: <>
Date: Thu, 14 Nov 2013 20:12:29 +0100
From: Maik Merten <>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0
MIME-Version: 1.0
References: <>
In-Reply-To: <>
Content-Type: text/plain; charset=ISO-8859-15; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [rtcweb] H261/MPEG-1 video quality (was: I'd love it if patents evaporated)
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Thu, 14 Nov 2013 19:12:41 -0000

Hello again,

to allow for having a quick look at some test sequences I put together a 
very very sloppy overview page at

This includes a completely JavaScript-based MPEG-1 player for those that 
don't happen to have a fitting decoder installed (also, yay, JavaScript 
is fast enough now for simple video decoders!). I recreated the encoded 
files to ensure there are no b-frames and documented the encoder 
settings accordingly.

Best regards,


Am 14.11.2013 11:52, schrieb Maik Merten:
> Hello all,
> in a
> sample of H.261 video was provided, connected to a (rhetorical?)
> question if this provided quality would be acceptable for users. Clearly
> that provided sample is of very low and unacceptable quality.
> Just for comparison, here are two CIF samples at roughly 256k created by
> a somewhat modern encoder (ffmpeg with rate/distortion optimization):
> (encoded as MPEG-1 video, as the "h261" encoder in ffmpeg crashes when
> using rate/distortion optimization. I understand MPEG-1 if used without
> b-frames is similar to H.261 in coding efficiency, but mostly adds more
> flexibility regarding frame sizes.
> ffmpeg -i sign_irene_cif.y4m -vcodec mpeg1video -mbd rd -trellis 2 -cmp
> 2 -subcmp 2 -g 100  -vb 256k irene-256k.mpg )
> Even without formal testing it is obvious that H.261 and/or MPEG-1 video
> is clearly outperformed in terms of coding efficiency by H.264 and VP8.
> However, personally, speaking as an end-user, I would very much prefer
> this video quality over audio-only calls (in cases where transcoding is
> not available), as the video produced still carries useful information.
> Also H.261/MPEG-1 is blazingly fast, can be dealt with in software, and
> is not exceedingly difficult to implement.
> Of course a MTI codec with higher coding performance is much preferable.
> However, if no such high-performance codec with licensing terms that are
> acceptable for all communities can be agreed on I think it may be wise
> to seriously evaluate the option of implementing an outdated codec for
> the sake of interoperability. In practice, most calls will negotiate to
> H.264 and VP8 anyways, but sporadic negotiation failures that are
> difficult to account for by the user are still to be expected if no MTI
> codec is defined at all.
> Best regards,
> Maik