Computers & Electronics

Netflix rolling out higher-quality audio with adaptive bitrate

  • Last Updated:
  • May 1st, 2019 9:50 pm
[OP]
Deal Addict
Jul 3, 2017
3860 posts
2784 upvotes

Netflix rolling out higher-quality audio with adaptive bitrate

Netflix previously used adaptive bitrate for video, increasing or decreasing the bitrate depending on what your connection could support. Now they are going to try the same approach with audio, allowing the audio bitrate to increase to higher rates than previously available for better sound. This will be available for Dolby 5.1+ audio streams, or Dolby Atmos streams for Premium accounts. Might only be available on Netflix in-house titles at the moment, with other titles depending on the quality of the master supplied to Netflix by outside sources.
https://www.cnet.com/news/netflix-now-s ... -watch-it/

Note the Netflix still only supports Dolby 5.1+ surround sound. If you have an older AV receiver that only supports regular Dolby 5.1 encoding, you are still out of luck.
9 replies
Deal Expert
Mar 23, 2009
18837 posts
4944 upvotes
Toronto
I'm curious how well this will work.

Compressed Dolby Atmos from Netflix via ARC is supposedly supported by my LG C8 OLED TV, but it doesn't seem to work with my HDMI 2.0 Marantz receiver. That shouldn't be a big surprise though, since HDMI 2.0 doesn't actually officially support Atmos over ARC. I'm not keen on buying an HDMI 2.1 receiver just yet esp. since my TV isn't HDMI 2.1 anyway so it's probably using some sort of non-standard method to transmit Atmos over ARC.

https://www.flatpanelshd.com/news.php?s ... 1534479331

Image

I'll let things settle and mature for a while before investing more money in a new receiver. However, even if I still can't get Atmos just yet, the good news is we should finally get some better 5.1 audio. The articles states 5.1 up to 640 Kbps and Atmos up to 768 Kbps. Hopefully this will be more the rule rather than the exception. The sound on Netflix was one spot where the experience really suffered, as it seemed they were keeping the bitrates quite low on most content, even though AFAIK 640 Mbps 5.1 audio has always been supported by the ARC specs.

I have Rogers Gigabit internet without significant congestion in my area, so hopefully that will translate to the best 5.1 sound they can offer whenever possible.
Deal Addict
Jan 17, 2009
2959 posts
2860 upvotes
Toronto, Ontario
ARC never works properly for me consistently even when everything supports it. It'll work great for a week and then stop working for a day and ill have to turn things off and on a few times for it to come back.. Better to just run everything through your receiver or use optical out.
Deal Expert
Mar 23, 2009
18837 posts
4944 upvotes
Toronto
Ecsta wrote: ARC never works properly for me consistently even when everything supports it. It'll work great for a week and then stop working for a day and ill have to turn things off and on a few times for it to come back.. Better to just run everything through your receiver or use optical out.
Well, you can't run Netflix audio from a ATV through your receiver except through ARC, unless as you suggest, you use the inferior optical out. However, the other problem is some TVs only output stereo over optical.

So, what I do is run all my separate devices through the receiver, but run Netflix from my TV via ARC. Luckily, after doing a lot of fiddling, I've gotten everything to work consistently, on two different systems in my house. Interestingly, on one system I could turn on the Atmos setting to transmit Atmos over ARC and sometimes output sound, but I don't think it was necessarily even Atmos, I got audio sync issues, and it was never reliable and like your system it'd stop working after a while. I then turned off all references to Atmos and now it all works perfectly, in perfect audio sync. Note I also have CEC turned off for everything else, so the only thing being transmitted back to the receiver from the TV is ARC audio.
Deal Expert
Mar 23, 2004
28285 posts
8741 upvotes
Exp315 wrote: Note the Netflix still only supports Dolby 5.1+ surround sound. If you have an older AV receiver that only supports regular Dolby 5.1 encoding, you are still out of luck.
You're not exactly out of luck because quality should still improve though you are still stuck with E-AC-3 transcoded to AC-3. One lossy format to another is never good. However E-AC-3 can go up to pretty good bitrates, but it seems unknown if all TVs supporting E-AC-3 (and therefore transcoding to AC-3) can support all bitrates. But regardless, higher bitrate to start is better since converting a better lossy stream to another format is still going to produce a better end result, even if the end result is limited to an older codec. Of course Netflix never used too high of bitrates anyway...

Netflix audio previously sucked pretty bad, so this is good news. E-AC-3 is considered "more efficient" than old-skool AC-3 so they were using fairly low bitrates all this time. While DD (AC-3) is limited to a max bitrate of 640kbps for all channels, DD+ (E-AC-3) can go much higher. However they were using way lower bitrates because Dolby of course claims :rolleyes: that DD+ is better at a low bitrate than is DD at full bitrate--which is a bit of a stretch (it is better, bit for bit, but not so much that a 192kbps E-AC-3 stream is better than a 640kbps AC-3 one I don't think).

The problem comes when you do not have DD+ compatibility in your AVR. In this case the DD+ gets transcoded to DD! Meaning you're taking a lossy format and converting it to another one, the results of which, at low bitrates, becomes quite poor. This is why DTS has always been better in this regard (backward compatibility) because they chose a "core and residual" format* with DTS-HD, requiring no transcoding to "fall back" to the older standard--hence no additional loss in quality. The sad part is though DTS-HD/MA quickly took the lead in BD titles in the beginning, there's no streaming services that seem to have used it; so with nonsense like DD+ we end up having to be stuck with transcoding going back to regular DD. Because of Atmos, Dolby regained some of the market in BD, though there at least there is typically the "hidden" AC-3 track in addition to the TrueHD track so stepping down means no transcoding either.

Personally I have an older AVR that supports multi-PCM from HDMI but not any DD+ or HD formats. This is perfectly fine for BDs since high quality (TrueHD or DTS-HD/MA) decoded audio is possible and doesn't affect anything. But for streaming services I'm always stuck with transcode-to-AC-3 crap. Hence I've always despised Netflix audio, though of course I live with it. At least now I can hope the transcoded audio becomes a bit better due to starting out at a better bitrate!

*TBH the "core & residual" scheme is one of the best ideas I think ever came to market for compressed audio schemes. Dolby screwed this up by doing the whole DD+ nonsense and choosing MLP for TrueHD. DD+ is just a dumb stopgap and incompatible [directly] with anything else. There's nothing wrong with MLP (it's perfectly fine as a lossless codec) but it has no downward compatiblity either so in the end it's just "wasteful". The only other core & residual scheme that comes to mind was Sony's ATRAC Advanced Lossless, which included ATRAC3 within it but since that was a highly proprietary format only used on Sony devices, it didn't really have much potential. DTS did this perfectly yet it only got heavy adoption on Blu-ray disc, unfortunately.
[OP]
Deal Addict
Jul 3, 2017
3860 posts
2784 upvotes
ES_Revenge wrote: The problem comes when you do not have DD+ compatibility in your AVR. In this case the DD+ gets transcoded to DD!
Sadly it doesn't. Netflix running on my Roku will only pass through DD 5.1+ to my old AV receiver, which doesn't understand it. Netflix won't transcode to DD 5.1, and neither will Roku.
Deal Expert
Mar 23, 2009
18837 posts
4944 upvotes
Toronto
^^^ Time for a new receiver. DD+ has been common for a decade now.

I’d recommend an HDMI 2.1 model once they are in their second generation.
Deal Expert
Mar 23, 2004
28285 posts
8741 upvotes
EugW wrote: ^^^
Time for a new receiver. DD+ has been common for a decade now.
Ha, not giving up my DA7100ES's Digital Drive amp :P If only Sony had not abandoned S-Master Pro :( I do have an AVR in a bedroom that has bitstreaming support for DD+/TrueHD/DTS-HD, but it's a lesser AVR so I'm not putting that in the living room just because it can do DD+. "Common" or not DD+ is mainly just foolishness. It was mainly made for HD-DVD and we see how far that went. After it satisfied the lowly demands of streaming because Dolby pretended like it was great at hilariously low bitrates :rolleyes:

DD+ at the terrible 192 rate, even natively decoded, isn't going to do anything great anyway. If Netflix has increased to 640kbps E-AC-3 that's not bad and the transcode should turn out much better. I've gotten so used to their crapass audio that it's not like I need DD+ decoding anyway. Wherever/whenever possible I go with BD...but there's lots of stuff I'm not going to buy and watch casually on Netflix.

I've occasionally thought about buying a Pioneer SC receiver to see how it does against my "old-skool" receiver but never found a good enough deal on one to bother. I don't need to upgrade for nonsense codecs that "never should have been" and newer features I don't really need either. I think the best deal I've seen on an SC in the retail mkt was when Gibby's had the refurb SC-85s but by the time I saw that deal they were sold out and never restocked. Apart from the SCs I'm not sure there's anything that will sound or perform similarly, amp-wise, speaking of an AVR anyway.

But whatever if I'm a 3D fan and can get away without a 3D-capable AVR just fine, along with maintaining lossless audio, pretty sure I don't need a newer AVR.
Deal Expert
Mar 23, 2004
28285 posts
8741 upvotes
Exp315 wrote: Sadly it doesn't. Netflix running on my Roku will only pass through DD 5.1+ to my old AV receiver, which doesn't understand it. Netflix won't transcode to DD 5.1, and neither will Roku.
On these kind of "smart devices" possibly not. On most other CE devices, like TVs, it should be possible (unless the TV doesn't support anything but 2ch PCM output when not using ARC/bitstreaming). All my TVs that have built-in Netflix will output standard DD by transcoding it. A PC will do it fine too, either over HDMI or S/PDIF.
Sr. Member
Jan 8, 2015
800 posts
509 upvotes
EugW wrote: ^^^ Time for a new receiver. DD+ has been common for a decade now.

I’d recommend an HDMI 2.1 model once they are in their second generation.
Common for a decade now yet my low end 2015 Sony TV(non-android) won't accept DD+ thru the built in DLNA media player nor transcode it to DD despite it saying it accepts the audio codec in the documentation. Frustrating.

Top