Re: [Rum] Distinguishing RUE and Provider requirements

Eric Burger <> Mon, 04 November 2019 15:40 UTC

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Date: Mon, 4 Nov 2019 10:39:50 -0500
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Subject: Re: [Rum] Distinguishing RUE and Provider requirements
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The point is that if we say it’s OK not to implement Opus, it means we will still be using G.711 in 2120, long after the last 3,000 Hz toll facility has crumbled into dust.

By saying Opus is Mandatory to Implement, it means you can feel free to use G.711 if that’s what is offered, but when you look in the other direction you are able to accept a more modern codec. Also, Opus is infinitely better for people with partial hearing loss than G.711 - it can be the difference between being able to still use audio, being able to use just a CTS service, or if needed a full VRS service. These are the kinds of things we think about in the IETF to support legacy networks while creating useful services that are not simply replicas of legacy services.

> On Nov 4, 2019, at 10:33 AM, Brian Rosen <> wrote:
> Mandatory to Implement doesn’t mean mandatory to use.  In the example of an incoming call from the PSTN, offering G.711 only is appropriate, and transcoding would not be advisable.
> The IETF folk understand MTI, but perhaps some explanatory text would be helpful in the document.
> Brian
>> On Nov 4, 2019, at 7:56 AM, James Hamlin < <>> wrote:
>> Paul
>> In the draft-ietf-rum-rue-00, there's an exemption from VP8 support for providers but no exemption from Opus support. The implication is that, in a call from the PSTN using Voice Carry Over, the provider must offer OPUS even though the audio content is constrained to 8bit*8kHz PCM over the PSTN. I don't recall seeing any argument for requiring transcoding in this case; there would be no benefit in audio quality.
>> Best regards
>> James
>> ________________________________________
>> From: Rum < <>> on behalf of Paul Kyzivat < <>>
>> Sent: 01 October 2019 20:15
>> To: <>
>> Subject: [Rum] Distinguishing RUE and Provider requirements
>> In the discussion thread that followed the attached message it started
>> to become apparent that there is a need to distinguish the requirements,
>> and/or requirement strength, that apply to the RUE itself from those
>> that apply when a RUE connects to a VRS Provider.
>> Now that we have a wg draft to work from, I would like to see people
>> step forward and make proposal(s) for what those differences should be.
>> While the prior discussion focused on codecs, please also consider what
>> else might need to differ.
>>        Thanks,
>>        Paul
>> -------- Forwarded Message --------
>> Subject: [Rum] Codec requirements in draft-rosen-rue-01
>> Resent-From: <>
>> Date: Mon, 12 Aug 2019 16:20:51 -0400
>> From: Paul Kyzivat < <>>
>> To: <>
>> draft-rosen-rue-01 changes the video codec requirements. It now simply
>> references webrtc RFC7742.
>> RFC7742 distinguishes three types of endpoints: "WebRTC browser",
>> "WebRTC non-browser", and "WebRTC-compatible endpoint". AFAIK it assumes
>> that each end is one of these.
>> Is the expectation here that both the RUE and the provider comply with
>> one of these? In particular, that the provider may simply be a
>> "WebRTC-compatible endpoint? Notably:
>>    "WebRTC-compatible endpoints" are free to implement any video codecs
>>    they see fit.  This follows logically from the definition of "WebRTC-
>>    compatible endpoint".  It is, of course, advisable to implement at
>>    least one of the video codecs that is mandated for WebRTC browsers,
>>    and implementors are encouraged to do so.
>> Similarly, the audio requirements have been changed to reference webrtc
>> RFC7874. That one doesn't have the distinction between "WebRTC browser",
>> "WebRTC non-browser", and "WebRTC-compatible endpoint". It applies the
>> same requirements to all. In particular, it requires OPUS support. I
>> don't know why it doesn't make the same endpoint distinctions as for video.
>> I think simply referencing these documents isn't sufficient. Seems like
>> we need a more nuanced specification of what is required, though we may
>> still reference these docs with qualifications.
>>        Thanks,
>>        Paul
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