MPEG4 tests - Not a Public Service

jobyrne30 wrote: »

I don't know if this has been mentioned before but RTENL_1 is running with 3 audio tracks

Audio #1
ID : 64 (0x40)
Menu ID : 137 (0x89)
Format : MPEG Audio
Format version : Version 1
Format profile : Layer 2
Duration : 2s 712ms
Bit rate mode : Constant
Bit rate : 192 Kbps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Video delay : -1s 637ms
Stream size : 63.6 KiB (7%)
Language : English

Audio #2
ID : 65 (0x41)
Menu ID : 137 (0x89)
Format : MPEG Audio
Format version : Version 1
Format profile : Layer 2
Duration : 2s 928ms
Bit rate mode : Constant
Bit rate : 192 Kbps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Video delay : -1s 635ms
Stream size : 68.6 KiB (8%)
Language : iri

Audio #3
ID : 66 (0x42)
Menu ID : 137 (0x89)
Format : MPEG Audio
Format version : Version 1
Format profile : Layer 2
Duration : 2s 712ms
Bit rate mode : Constant
Bit rate : 64.0 Kbps
Channel(s) : 1 channel
Sampling rate : 48.0 KHz
Video delay : -1s 548ms
Stream size : 21.2 KiB (2%)
Language : English

Yes,
audio 1 is the main soundtrack, I am hearing the radio voiceover
audio 2 is the testcard sound
audio 3 is total silent
So I am wondering if there is going to be a duel language, English and Irish and the 3rd audio is the Audio Description for the blind

MYOB wrote: »

They're taking an awful long time to lock for me - are they AAC instead of MP2 by any chance?

No, but they are running at a reduced bitrate of 128 kbps compared to the others.

are the channels currently running at mp2 or are most of them at mp4 (not too sure what my nova-t card is capable of)? also i am picking up the following but no tv3 - how does this compare to what everyone else is recieving -

mount leinster

rte 1
rte 2
TV3 IS MISSING
rteNL 1 (nothing broadcasting - just a still with some music)
TG4
rte news now
rteNL 2 (nothing broadcasting - just a still with some music)
rte radio 1
rte 2 FM
rte RnaG
rte radio 1 extra
rte Pulse
rte 2XM
rte Choice
rte Gold
rte Chill/ rte junior

using a nova-t wintv stick with windows 7 meadia centre and full EPG - sorry if ye have to repeat yourselves lad and ladies - i am new to all this DTT tech

Thats exactly what I have. No TV 3 though, and RTÉNL 2 is a HD caption so hopefully some HD tests will start soon!

Eternal Wonderer wrote: »

Thats exactly what I have. No TV 3 though, and RTÉNL 2 is a HD caption so hopefully some HD tests will start soon!

I'm wondering just how RTENL are going to manage any kind of decent HD quality (bitrate) unless they move the HD channel to a separate multiplex? I've done some "back of the envelope" calculations based on what the DVBviewer Transedit software on my PC is telling me. According to it the overall bitrate of the multiplex is a shade over 24Mpbs, with only about 3.3Mbps "spare" (transmitted as null packets) at the moment. The RTENL2 (HD) channel is transmitting a test card at about 2.1Mbps at present. Any kind of decent HD quality on MPEG4 would need at least 10Mbps (a la BBC or ITV HD which is sub-sampled 1440x1080i), or ideally about 12Mbps according to the EBU but there doesn't seem to be that capacity left on the multiplex. Even as it is, the resolution is less than optimal (544x576 instead of 720x576) on RTE1, TG4 and the "placeholder" for TV3 (RTENL1), so there is little room to squeeze spare bitrate. Or have I missed something in my calculations? The EBU GE06 plan indicates a max capacity of 27Mbps in a DTT multiplex so RTENL are already close to this. Comments / views?

Here are the bitrates reported by DVBviewer ( note these vary depending on programme content and how the stat mux is setup, but they are typical over a 15 min period):

RTE1 video 2.3Mb
RTE2 video 4.4Mb
RTENL1 1.5Mb
TG4 3.3Mb
RTEnews 2.3Mb
RTENL2(HD)2.1Mb

so about 16Mb/s for video.
The 10 audio channels for tv take another 1.5Mb/s
The 10 radio channels take about 1.5Mb/s
EPG and teletext take about 1Mb/s
MHEG another 1Mb/s

Total 21Mb/s -ish plus 3.3Mb/s padding

This is why DTT HD is inferior to BD or Satellite.

BD peaks at over 24Mbps.

Satellite uses 7 to 9Mbps with 18Mbps peaks using 1920x1080i real widescreen (not anamorphic).

I estimate that they will use 5Mbps to 6Mbps with 10Mbps peaks as allowed by stat mux and required by program content. OK for HD on 37" set in a big room. Rubbish compared with Blue Ray when you have 48" to 60", which is what HD was invented for. Decent up-scaling is hardly distinguishable from 1440x1080 on a 32" TV in a typical room.

DTT HD is going to be inferior. Lower quality to reduce bitrate and also lower resolution of 1440x1080i, i.e. anamorphic WS.

Is this why BBC has lowered the Satellite HD quality, so as to have less difference with the DTT HD which soft launched last December approx.

If you did the quality that BBC HD test was initially on Satellite, you only fit 2 or 3 HD channels per DTT mux.

If you do DVD quality on DTT, even with H.264 you'll only get 5 to 6 TV channels and no Radio and no MHEG. If you do Sky Shopping channel quality you can fit 10 TV channels or more.

Like DAB vs FM, Digital TV only gives better than Analogue good Signal if you are not greedy. There should be 4 PSB mux, no Pay TV and All HD from the start to avoid simulcast. A setbox will convert for non-HD TVs.

watty - what I fear is the trade-off of quality. Just because you can squeeze umpteen shopping-type channels into a DTT mux, doesn't mean you should.
We are already seeing the reduction in resolution (544x576) in all of the channels except RTE2 (why is RTE2 at full resolution though - surely RTE1 should be the preferred child!) and this is before the thing goes properly live. I've witnessed BBCHD drop the bitrate from 16Mb/s on satellite to approx 9Mb/s last year. One can only assume that the reason is a convergence with DTT bit rates.

Has no-one else noticed that RTE Choice has had one channel out of phase since it reappeared?
Or else they're experimenting with pseudo-spatial-surround encoding on a talk channel

RTE Gold & Chill have balance issues also, Gold too much to the right, Chill too much left.
I hope they keep these on DTT, I think they've a lot of worthwhile content.

rurs wrote: »

Has no-one else noticed that RTE Choice has had one channel out of phase since it reappeared?
Or else they're experimenting with pseudo-spatial-surround encoding on a talk channel.

RTE Gold & Chill have balance issues also, Gold too much to the right, Chill too much left.
I hope they keep these on DTT, I think they've a lot of worthwhile content.

Something strange with the sound on Choice alright. Just listening to a news programme there which is from a mono source. If you select the left channel or the right channel only it comes up centrally in the headphones, but when both are selected there is a kind of a spatial effect. I'll see if I can resurrect a copy of Cool Edit to see if I can look at the waveforms.

As another observation, both RTE Radio 1 and Radio 1 Extra are in mono on DTT and at 96kbps (other radio programmes are at 128kbps stereo). On the satellite platform Radio 1 is in stereo at 192kbps. Radio 1 is predominantly talk radio, but they do have music programmes at midday and also late at night.

Another way to here the difference is to flick between Choice and World Service simulcasts, of which there are several every day.

The "effect" will be less noticeable on headphones, you need to have your head in the middle of the stereo field, between two speakers.

Maybe the RTE engineers are doing their monitoring on headphones?

Interesting...presumably it was fixed sooner rather than later?

It's probably a silly question but what exactly is RTNL 1 and RTNL 2? Does RTE intend to launch two more stations or what?

craoltoir wrote: »

RTÉNL 1 is reserved for TV3 when DTT is officialy launched. RTÉNL2 is, at the moment, a HD test.

ive seen no broadcasts on RTE NL 2 - was there any or is it for future HD tests?

STB wrote: »

Regardless of EU legislation what you should be referring to is the Broadcasting Act 2009.

Sorry to inform you mate but E.U. regulation overides that act.