NON-freeview TV sound quality has deteriorated

Forums › Home Theatre (including HTPC and EPG Collector) › NON-freeview TV sound quality has deteriorated

1 | 2

paradoxsm

3000 posts

Uber Geek

Trusted

#124221 16-Apr-2008 23:17

The problem with AAC+ is is uses a quite a different coding method for the high frequency portion which can lead to artifacts. For the bandwidth they have available and the high definition video they are using they should have just gone with Low-Complexity AAC at 192KBps

My take on the codecs from years of encoding and doing dev work.

AAC+ is good from about 24Kbps to 64KBps
It's a low bitrate hybrid codec made mainly for telephony applications. Any higher is a waste and can introduce atrifacts due to coding method used (Replication) as it's designed to be used for ultra-low bitrate coding.
AAC is good from about 96Kbps to 160KBps
AAC can sound quite flat and becomes pretty negligable after 160KBps
MP3 is good from about 160Kbps to 256KBps
Any lower can sound "watery" and any higher is practically transparent to CD in most user applications.
MP2 is good from 192Kbps to 384Kbps
MP2 is very old but very robust and compatible and it sounds good at high bitrates.

I'll tune into analog tomorrow with a proper scanning reciever and take a listen, I wonder about NICAM???

Quic Broadband

Move to New Zealand's best fibre broadband service (affiliate link). Note that to use Quic Broadband you must be comfortable with configuring your own router.

dabade

12 posts

Geek

#124240 17-Apr-2008 00:59

Well, I don't want to drag this off topic, but I googled my way into this thread because I initially heard the quality of freeview HD and was stunned by both how good it looked, and bad it sounded.

I respect that AAC is a different codec from MP3 and bit-rate milage may vary, I also don't claim to know the intracacies of each codec, but perceptually with my ears this is just not up to snuff. At 128kbps like tv3 and c4 it seems to be acceptable, but down at the 50-60kbit mark it's a shocker. The worst appears to be a loud noise after silence, when a sort of joint stereo after-shock seems to occur causing me to twist in my seat ala chalkboard nails

. ALso, I'm sure there are some people out there WITHOUT a lisp :-) . Not really my idea of crystal clear.

I'm really interested to hear what paradoxsm discovers about the non-freeview audio. Maybe it varies from region to region?
I don't currently have my TV/receiver wired for analog, but I'll plug it in tomorrow and compare.

openmedia

3290 posts

Uber Geek

Trusted

#124281 17-Apr-2008 09:13

dabade - Are you using a PC or an official STB?

Some people have codec issues with PC playback that might be the cause of some of your problems.

Generally known online as OpenMedia, now working for Red Hat APAC as a Technology Evangelist and Portfolio Architect. Still playing with MythTV and digital media on the side.

cyril7

9050 posts

Uber Geek

ID Verified

Trusted

Subscriber

#124286 17-Apr-2008 09:23

I'll tune into analog tomorrow with a proper scanning reciever and take a listen, I wonder about NICAM

Cannot comment on non BCL/TVNZ analog Txs but TV1/2 is delivered to the Tx site as NICAM on the Digital Microwave Network from the studio, an analog mono mix is pulled off the NICAM feed at the transmiter site to feed the FM side, so same source for both.

I dont listen/watch analog TV anymore, havent for years, but I do know that the FreeView sat audio is well ahead of Skys, pity if the AAC-HE DTT stuff is a step backward, well from what you guys describe.

Cyril

richms

27963 posts

Uber Geek

Trusted

Lifetime subscriber

#124330 17-Apr-2008 11:03

I have heard dvb-t on a proper box via optical into a decent HT system, and it sounded just as crap as my one on the PC at home did.

And yes, the sound on analog's nicam seems to be suffering on the same HT system.

I have my junk stereo hooked up at home and have noticed the crap quality isnt just my tv speakers. Hard to compare since its being so long since I have heard analog tv's sound on a proper system but I dont recall C4 being virtually unlistenable - then again that may just have being the poor excuse for mastering that happens with contempary music vs the transmission path ;)

Richard rich.ms

Batman

Mad Scientist
29687 posts

Uber Geek

Trusted

Lifetime subscriber

#124352 17-Apr-2008 11:46

sounds like we're off on a tangent but all the more reason to do so!!

sounds like (pun not intended!) freeview HD is just free VIEW in hi def, minus the sound part! ok i'm now in no hurry to get the overpriced zinwell box :) wait till a pvr comes out

dabade

12 posts

Geek

#124427 17-Apr-2008 16:21

@ openmedia.

using a p4 3.2 pc with 7950gt and HVR-4000 and the bundled powercinema software, also use powerdvd8 codecs.

I record the stream and then analyse it.

dabade

12 posts

Geek

#127140 29-Apr-2008 18:59

FYI, analog TV sounds fine here (hamilton).

On another forum I discovered the presence of a second stream on some channels / namely AC3, however even though the PIDS are valid (usually add 10 to the standard audio pid) , there is no audio currently on the AC3 streams (I wonder if it will turn on when there is a movie?). I understand that these were used during testing earlier (but just in stereo), bt may not be in use because some beople get confused when thier decoders say "dolby digital" but only shot 2 channels.

ANyway, since TV3/C4 are not as bad (audio wise) as the TVNZ channels, I've started wtaching news on tv3 instead of TV1.

paradoxsm

3000 posts

Uber Geek

Trusted

#127290 30-Apr-2008 13:20

Alas, my plans to scan the airwaves were thwarted, My trusty super-sensitive old Radioshack scanner has finally bitten the dust due to a cheap (transonic) faulty battery that has leaked. The keypad was constructed from carbon printed traces like many TV remotes and the battery alkalines have dissolved this into a black slusge..

Scott P has given me a good suggestion for a scanner, I would prefer one that can transmit outside the amatuer bands, even if it requires a hardware or software hack. I'd assume the filtering would only allow out a flea power outside it's native ranges but that's fine as an "in field" asignal generator.

dabade

12 posts

Geek

#127322 30-Apr-2008 15:52

Here I am again off subject But, here is a response from freeview about the audio quality.

---
Hi Raymond,

TVNZ are currently doing upgardes and working there best to correct this. We do apologise for the inconvenience

Thanks for your enquiry
Freeview team

-----Original Message-----
From: freeview
Sent: Mon 4/28/2008 8:36 AM
To: Agent 021
Cc:
Subject: Freeview Website Feedback

Name: Raymond van Driel
Email:<removed>

Comments / Questions:
I live in Hamilton, and use freeview DVB-T, I would like to ask why the audio (HE AAC at ~60kbit) for the TVNZ stations is really of such a low quality, it really lets down the otherwise excellent service, HDTV and AM quality audio makes no sense at all to me.

---

Disrespective

1921 posts

Uber Geek

#127474 1-May-2008 09:52

FWIW I've recently been relegated back to 'normal' TV rather than the Freeview goodness and have noticed that the audio quality is definitely worse than i remember. There is obvious crackling and hiss with what i remember from a month or two ago. All this is making me yearn for the freeview even more than ever now.

1 | 2