- From: Stojiljkovic, Aleksandar <aleksandar.stojiljkovic@intel.com>
- Date: Wed, 30 May 2018 20:01:55 +0000
- To: Randell Jesup <randell-ietf@jesup.org>, "harald@alvestrand.no" <harald@alvestrand.no>, "public-webrtc@w3.org" <public-webrtc@w3.org>
- Message-ID: <7A0FAB90EDAE304EA98E76ACB132D51233254732@IRSMSX103.ger.corp.intel.com>
Fair enough, both are valid points. I thought it was good to reopen timestamp approach. For the reference - clock resolution security issues [1]. Android camera defines the timestamp as sensor capture start time [2]. Note that SENSOR_INFO_TIMESTAMP_SOURCE could have value UNKNOWN and we would get monotonic time, that cannot be compared to timestamps from other subsystems, e.g. sensors. [1] https://www.w3.org/TR/hr-time/#clock-resolution<https://www.w3.org/TR/hr-time/#clock-resolution.> [2] https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics#SENSOR_INFO_TIMESTAMP_SOURCE Kind Regards, Aleksandar ________________________________ From: Randell Jesup [randell-ietf@jesup.org] Sent: Wednesday, May 30, 2018 7:53 PM To: public-webrtc@w3.org Subject: Re: Raw data APIs - 2 - Access to unencoded data On 5/30/2018 8:10 AM, Harald Alvestrand wrote: Den 30. mai 2018 13:42, skrev Stojiljkovic, Aleksandar: Interface Buffer ... Long long timestamp; // for start of buffer. Definition TBD. Maybe DOMHighResTimeStamp <https://www.w3.org/TR/hr-time/#sec-domhighrestimestamp><https://www.w3.org/TR/hr-time/#sec-domhighrestimestamp>, to enable sync with other events, e.g. Sensor interface <https://www.w3.org/TR/generic-sensor/#the-sensor-interface><https://www.w3.org/TR/generic-sensor/#the-sensor-interface>. DOMHighResTimeStamp is convenient for absolute times, when it's clear what it's related to (time the light hit the camera sensor?). For playback of stored media, we might want to use a clock relative to the start of the media; I know there are various well known apps for doing things like time-stretching of videos - I'm not sure how that would be representable in an API. I'll note that any use of high-resolution timers by apps may be constrained by the wonders of Spectre mitigation for some time. It would be nice to un-fuzz the timers, but even once one has implemented fission/site-isolation/whatever-edge-will-call-it, lots of high-res clock sources make it super-easy to do spectre attacks. :-( -- Randell Jesup -- rjesup a t mozilla d o t com Please please please don't email randell-ietf@jesup.org<mailto:randell-ietf@jesup.org>! Way too much spam --------------------------------------------------------------------- Intel Finland Oy Registered Address: PL 281, 00181 Helsinki Business Identity Code: 0357606 - 4 Domiciled in Helsinki This e-mail and any attachments may contain confidential material for the sole use of the intended recipient(s). Any review or distribution by others is strictly prohibited. If you are not the intended recipient, please contact the sender and delete all copies.
Received on Wednesday, 30 May 2018 20:02:27 UTC