johnhb 7 Posted January 4, 2021 Share Posted January 4, 2021 A serious question for the streaming box proponents - what streaming box can do all the following with my local media files? Sample accurate gapless audio (because we had that with CD players in the 70s ffs) Bit perfect audio where the digital output matches the sampling rate and bit depth of my source files and doesn't impart some arbitrary DSP enhancement (because some poor b**stards spent hours mixing and mastering my music and I want to hear what they wanted it to sound like - well as close to that as possible) Frame rate switching (because good video quality is hard enough to achieve without avoidable interpolation) 1:1 pixel mapping at native resolution (because.. see previous) Audio sync compensation with separate settings for 23, 24, 50 and 60 Hz - because refresh rate switching is needed and every TV I've ever used delays audio by nearly 200 ms at 24 Hz compared with other modes (humans demonstrably tolerate -30 to +20 ms delay wrt video) Convince me otherwise, but so far streaming devices to me seem like a race to the bottom in terms of quality. I don't really want to be stuck in a world where everything's poorly converted to 60P or the audio chain is a black box of DSP I never asked for or the content I've paid for vaporises overnight. Link to comment Share on other sites More sharing options...
vdatanet 1549 Posted January 5, 2021 Share Posted January 5, 2021 (edited) 9 hours ago, johnhb said: A serious question for the streaming box proponents - what streaming box can do all the following with my local media files? Sample accurate gapless audio (because we had that with CD players in the 70s ffs) Bit perfect audio where the digital output matches the sampling rate and bit depth of my source files and doesn't impart some arbitrary DSP enhancement (because some poor b**stards spent hours mixing and mastering my music and I want to hear what they wanted it to sound like - well as close to that as possible) Frame rate switching (because good video quality is hard enough to achieve without avoidable interpolation) 1:1 pixel mapping at native resolution (because.. see previous) Audio sync compensation with separate settings for 23, 24, 50 and 60 Hz - because refresh rate switching is needed and every TV I've ever used delays audio by nearly 200 ms at 24 Hz compared with other modes (humans demonstrably tolerate -30 to +20 ms delay wrt video) Convince me otherwise, but so far streaming devices to me seem like a race to the bottom in terms of quality. I don't really want to be stuck in a world where everything's poorly converted to 60P or the audio chain is a black box of DSP I never asked for or the content I've paid for vaporises overnight. Using Nvidia Shield with Android Mobile app (not Android TV), it can: Gapless audio playback Audio Hi-res playback without downsampling (AVR shows correct sample rate) Frame rate switching Android TV app handles better frame rate switching but it can't: Gapless audio playback Audio Hi-res playback without downsampling (AVR shows correct sample rate) Edited January 5, 2021 by vdatanet Link to comment Share on other sites More sharing options...
johnhb 7 Posted January 5, 2021 Share Posted January 5, 2021 (edited) That's useful to know, thanks! So Android TV is a no go because it will judder like crazy or have to perform unnecessary frame rate interpolation to try and smooth out non-native frame/refresh rates. The former will be obvious on panning scenes and probably causes mild headaches over time. The latter will mess up clarity and probably mucks with dynamic range because interpolation will dull whites and wash out blacks. Kind of makes HDR a joke, but hey, marketing's powerful right?! I heard gapless is hit and miss with android TV, presumably because of the infinite hardware possibilities - I guess that's probably the same for all features. With the shield, can you set different audio delays (+ and - ) for different refresh rates? For example, both my current TVs (Samsung) in 23.976/24 mode put audio ~180 ms ahead of video, it's spot on at 25 and 60 ms behind with 29.97. Every TV I've used in the past has exhibited similar behaviour (but to varying degrees) so I would imagine this is the same for just about everyone. This is on calibrated sets with image enhancements switched off. You have to bear in mind if you enable enhancements these can also change the relative delays for obvious reasons. Not sure what the implications are for AV sync with VRR, but notionally it sounds like a sensible thing to move to if the audio clock is similarly compensated (not sure where that leaves bitstreaming Dolby/DTS etc. but presumably there's a solution). In case it's of any use - I'm not affiliated in anyway whatsoever - short of spending 100s on a proper hardware AV sync tool, this app is pretty good for taking out the guesswork with AV sync https://quietart.co.nz/catchinsync/ Sorry more question .... Do these devices can compensate for clock drift between source (the streaming box) and sync (your TV) and handle dropped/missing frames (either from uncorrectable encode errors on source files of from uncorrectable transmission/transport errors) to keep AV sync? Because once you sort out the fixed delays of your playback chain, this can cause AV to drift over time (which is why a 2 hour movie can look fine at the start and unwatchable by the end). I believe that on PC MadVR/Kodi and JRiver all have solutions for the former and, for example, LAV audio has an option to tackle the latter. A quick scour of the Internet and the countless complaints about sync, video quality and other AV quality issues with all the streaming boxes tells me they don't, but I've yet to find anyone who has properly tested them. Edited January 5, 2021 by johnhb Link to comment Share on other sites More sharing options...
ebr 14939 Posted January 5, 2021 Share Posted January 5, 2021 3 hours ago, johnhb said: So Android TV is a no go because it will judder like crazy or have to perform unnecessary frame rate interpolation to try and smooth out non-native frame/refresh rates. No, that is incorrect. The Android TV app can perform frame-rate switching on hardware that supports it. Link to comment Share on other sites More sharing options...
johnhb 7 Posted January 5, 2021 Share Posted January 5, 2021 (edited) deleted Edited January 5, 2021 by johnhb Link to comment Share on other sites More sharing options...
johnhb 7 Posted January 5, 2021 Share Posted January 5, 2021 23 minutes ago, ebr said: No, that is incorrect. The Android TV app can perform frame-rate switching on hardware that supports it. Cool - and can you compensate for the fixed delay you'll probably get at different refresh rates ? Link to comment Share on other sites More sharing options...
ebr 14939 Posted January 5, 2021 Share Posted January 5, 2021 1 hour ago, johnhb said: Cool - and can you compensate for the fixed delay you'll probably get at different refresh rates ? We simply put the display into the mode that is closest to the frame rate of the source content (or doubled). Link to comment Share on other sites More sharing options...
johnhb 7 Posted January 5, 2021 Share Posted January 5, 2021 (edited) Sure, if the source is 23.976 and the TV supports it, you output 23.976 and the TV switches to 23.976. The problem is that just about all TVs take different amounts of time to present different frame rates so you need to allow users to compensate per refresh rate. To make it worse different TVs may impart different delays at different refresh rates and with different settings so only the user can reliably determine this. It's a massive pain but there's no getting away from it. The only exception (I would imagine) is if you use the analogue or SPDIF audio out on the TV, in which case as long as the player is outputting a sync'd stream the TV *should* do the compensation internally. But this doesn't help people who are running external DACs/AVRs. At least the flexibility of HTPCs lets us select software that allows us to do this. Edited January 5, 2021 by johnhb Link to comment Share on other sites More sharing options...
rbjtech 4291 Posted January 5, 2021 Share Posted January 5, 2021 The Shield also has Audio advance (+/- 10mS up to 1 Sec) if required from HDMI Sources and of course any decent AV Receiver is going to have Audio delay should you need it. I've played long running (3hr+) over the shield with refresh rate switching (to 29.976) on my LG C8 and have experienced zero sync issues with out the box settings on both my Denon AV and Shield. Link to comment Share on other sites More sharing options...
jrwalte 17 Posted January 5, 2021 Share Posted January 5, 2021 Same. Have a Shield to Denon to HDFury Diva to TV and I've never had a noticeable audio sync issue with streaming apps or Emby on the Shield. Denon audio sync is set to Auto. Link to comment Share on other sites More sharing options...
johnhb 7 Posted January 6, 2021 Share Posted January 6, 2021 (edited) If your source files are 29.976 and UI is 60p then your TV is not switching form 60 Hz. Edited January 6, 2021 by johnhb 1 Link to comment Share on other sites More sharing options...
johnhb 7 Posted January 6, 2021 Share Posted January 6, 2021 (edited) This makes quite interesting reading: Input Lag of TVs - RTINGS.com This is from the perspective of gaming, but actually the data is fully relevant to our case of AV sync where A and V are separated and the lag they measured here is part of what needs to be compensated. They only covered 60 Hz+ at different picture modes and 1080/4K but, well, you get the picture. It's quite a mess. In fact it reveals another issue I didn't cover - the lag can be different at different resolutions for the same FPS I'm not aware of any players that allow resolution and frame rate specific delay compensation to be set. They missed a trick with this article really - Input lag only matters for playing video games, either on a console or on a PC - well, yes it does in the real-time sense for gaming, but the delay is also a pain for AV sync when you split the audio from the video and need to (a) know what it is for the respective modes and (b) for the respective settings to kick in automatically when you play a new file - like all the self-respecting HTPC players have been doing for years. I looked up the shield - it allows ONE setting for AV sync using it's bouncing ball thingy. So the best you can do is get it right for one ONE refresh rate/resolution, then decide are you going to compromise on video quality and disable refresh rate switching or compromise on sync for all but one setting. Edited January 6, 2021 by johnhb Link to comment Share on other sites More sharing options...
rbjtech 4291 Posted January 6, 2021 Share Posted January 6, 2021 18 hours ago, johnhb said: If your source files are 29.976 and UI is 60p then your TV is not switching form 60 Hz. Maybe on your setup - but on mine the frame rate switches as it should - as proven by the inbuilt LG HDMI Diagnostics (*) The 60Hz is on the GUI - the 24Hz switches when I press play - it dynamically changes on the screen in front of my eyes ... (*) for all those with an LG - this is accessed by selecting the 'Programme Tuning' menu and then pressing '11111'. I think the C9+ owners get more info as they have a further option to click HDMI details but as I only have a C8, I do not have this option. Link to comment Share on other sites More sharing options...
johnhb 7 Posted January 6, 2021 Share Posted January 6, 2021 (edited) On 05/01/2021 at 16:54, rbjtech said: The Shield also has Audio advance (+/- 10mS up to 1 Sec) if required from HDMI Sources and of course any decent AV Receiver is going to have Audio delay should you need it. I've played long running (3hr+) over the shield with refresh rate switching (to 29.976) on my LG C8 and have experienced zero sync issues with out the box settings on both my Denon AV and Shield. You didn't say anything about 24 Hz in your original post. I was just using your example as an example. Now you've changed your example Edited January 6, 2021 by johnhb Link to comment Share on other sites More sharing options...
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