Digital TV video bitrates – January 2011

Time to update the video and audio bitrates for digital TV again in the light of the introduction of the new channel ‘Eleven’. (The last update was in October last year.)

To gather this data, on 18 through 20 January I  recorded at least six hours, in three separate chunks, from each station onto a Topfield PVR. Then I whacked the minutes and megabytes into a spreadsheet, did the division and subtracted the audio bitrate. These figures probably overstate things a little, depending how much extra the Topfield adds into its recording stream (not much, I imagine, because they are standard MPEG files), and the presence of subtitles. So, really, only the first two significant figures of the video bitstream should be considered.

Also, remember, this is in Canberra. The figures may well be quite different elsewhere. Our commercial stations still broadcast their HD as 1,440 x 1,080, for example.

If anyone would like to repeat the process in a major capital city, I’d be happy to email through the spreadsheet on condition that you provide the information back for publication here in due course.

Station Ch Audio
format
Audio
bitrate
(kbps)
Video
resolution
Average
video bitrate (Mbps)
ABC1 2 MPEG 2.0 256 720 x 576i 4.95
ABC2 22 MPEG 2.0 256 720 x 576i 4.04
ABC3 23 MPEG 2.0 256 720 x 576i 3.97
ABC News 24 24 DD 2.0 256 1280 x 720p 9.12
SBS ONE 3 MPEG 2.0 192 720 x 576i 4.12
SBS TWO 32 MPEG 2.0 192 720 x 576 4.15
SBS HD 30 MPEG 2.0 192 1280 x 720p 9.37
SC10 Canberra 5 MPEG 2.0 256 720 x 576i 5.14
ELEVEN 55 MPEG 2.0 256 720 x 576i 4.17
One HD Canberra 50 DD 2.0 448 1440 x 1080i 11.47
PRIME Canberra 6 MPEG 2.0 256 720 x 576i 5.06
7TWO Canberra 62 MPEG 2.0 256 720 x 576i 4.64
7mate Canberra 63 DD 2.0 256 1440 x 1080i 9.99
WIN Canberra 8 MPEG 2.0 384 720 x 576i 4.94
Canberra GO 88 MPEG 2.0 384 720 x 576i 4.58
GEM Canberra 80 DD 2.0 448 1440 x 1080i 9.72

ELEVEN has come at the expense of about 1Mbps from SC10 Canberra, and about 2.5Mbps from One HD Canberra. TEN and PRIME had rock steady bitrates across the three different recordings (max variance: 0.02Mbps), while WIN’s varied a little (max: 0.14Mbps), SBS a bit more (max: 0.34Mbps) and ABC quite a bit (max 0.86Mbps). I suspect that ABC at least actively manages its bitrate allocation according to programming requirements.

Update (11:13 am): fixed the audio bitrates and, consequently, the video bitrates on ABC News 24 and GEM Canberra. The former has reduced its bitrate, while the latter has reverted to a largely unnecessary 448kbps.

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4 Responses to Digital TV video bitrates – January 2011

  1. Tim Wainwright says:

    Hi

    What I am curious about is why 7 and 9 are re-broadcasting old, mostly 4:3 programming on GEM and 7mate at the expense of recent HD material. This is at the expense, for example, of the the Australian Open in stunning SD while I can watch Scrubs and The Family Guy at close to 10mbps! At least with OneHD, Ten are making an effort to utilise the bandwidth for high quality sports programming.

    It makes no sense to me at all. I suspect however that the issue lies with regulation and what the networks can and can’t broadcast on each channel.

    If you know, can you enlighten us with a column?

    Cheers
    Tim

  2. Stephen Dawson says:

    I think it’s partly regulation, and partly chance. Regulation requires all broadcasters to have a HD channel. The content doesn’t have to be in HD, but the signal must be in one of the approved formats (576p, 720p or 1080i).

    The chance part is to do with how the different networks decided to expand their offerings. Ten obviously focused on its HD channel first and chose a sports emphasis. A lot of US-sourced sports is in HD, so we get decent image quality on stuff which may be of marginal interest. The other two focused on their second SD station, and seem to been pleasantly surprised by the ratings for showing mostly old TV shows. So when they got around to thinking of what to do with their HD channel, they just repeated the formula.

    A thorough waste, I agree, but it looks like we’re stuck with it. That single 20/20 cricket match broadcast at the start of summer in HD looked glorious. Pity it was the last one.

  3. Tim Wainwright says:

    Yup, a real waste. I can download a HD copy of a recent show sooner than any of the main commercial channels show it here in SD. Go figure!

  4. Al says:

    It’s bizarre, it’s typical government stuff up in that case. Yes all should have a hd channel. But doesn’t matter they’re not showing hd material on it. Infact worse still they’re just putting any old reruns of Old 4:3 stuff, even worse very annoyingly they’re also cropping and zooming the picture on these to show them in 14:9 ?????

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