Digital TV video bitrates – May 2011

More advertising has recently hit our regional TV stations in the form of a channel called ‘GOLD’ using part of the WIN TV spectrum (it’s on Channel 84). Which, of course, prompts me to update the table of video bitrates. The last update was in September last year.

To gather this data, on 14 through 16 May 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 MPEG2 256 720 x 576i 5.12
ABC2 / ABC4 22 MPEG2 256 720 x 576i 3.96
ABC3 23 MPEG2 256 720 x 576i 4.15
ABC News 24 24 DD 2.0 256 1280 x 720p 8.36
SBS ONE 3 MPEG2 192 720 x 576i 4.53
SBS HD 30 MPEG2 192 1280 x 720p 9.27
SBS TWO 32 MPEG2 192 720 x 576i 3.85
SC10 Canberra 5 MPEG2 256 720 x 576i 5.14
One Canberra 50 DD 2.0 448 1440 x 1080i 11.46
ELEVEN 55 MPEG2 256 720 x 576i 4.18
PRIME7 Canberra 6 MPEG2 256 720 x 576i 4.70
7TWO Canberra 62 MPEG2 256 720 x 576i 4.74
7mate Canberra 63 DD 2.0 256 1440 x 1080i 8.59
4ME 64 MPEG2 128 544 x 576i 2.72
WIN Canberra 8 MPEG2 384 720 x 576i 4.69
GEM Canberra 80 DD 2.0 448 1440 x 1080i 8.22
GOLD 84 MPEG2 192 480 x 576i 1.46
GO! Canberra 88 MPEG2 384 720 x 576i 4.22

Things to note:

  • Several of the stations have changed their text names, usually just a little (‘Canberra GO’ is now ‘GO! Canberra’ for example)
  • If you can believe the last table I did, then Prime has made significant technical changes to its advertising channel, 64. It has changed the display resolution from 720 x 576 to 544 x 576. Actually, I hadn’t realised that 544 is a valid horizontal resolution. Presumably Prime reckons that reducing the number of pixels by nearly 25% yields benefits in terms of reduced compression artefacts. It has also halved the audio bitrate to 128kbps, which is a sensible move since it will make little difference to the sound but those few extra bits might make a slight improvement to the video.
  • The new station GOLD has an incredibly low video bitrate of less than 1.5Mbps! Again, the pixels have been reduced, with this one to 480 x 576, a full third below the norm. WIN has given it an audio bitrate of 192kbps, which is still a bit much, really. When you’re at video bitrates this low, even an extra 0.064Mbps could help.
  • WIN still wastes lots of bits on audio for all its stations: 384kbps for the two SD ones and 448kbps for its HD station. Bringing the SD ones down to 192kbps would bring them into line with the bulk of 2.0 audio on DVD, and given that the HD is rarely if ever in 5.1 mode, 448kbps is a bit over the top.
  • Southern Cross Capital (the 5* stations) and Prime (6*) seem to have a basically fixed bitrate for each of their channels, while the others seem to shift bits between channels, presumably according to need. The most extreme is ABC, which seems to boost the other channels (2, 22 & 24) overnight after its Kids Channel (23) shuts up. Oddly, it still uses a rather hefty 2Mbps for broadcasting a static panel on 23.
  • The winner for HD bitrate — by a long, long margin — is One Canberra at 11.91Mbps. The next highest is SBS HD, a 720p station, with its routinely poor, upscaled SD. The other HD stations are around 8.5Mbps.
  • The winner for SD bitrate is SC10 Canberra, closely followed by ABC1. But while SC10 was 5.14Mbps on all three clips, ABC1 was widely varied: 5.74, 5.05 and 4.57Mbps.
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2 Responses to Digital TV video bitrates – May 2011

  1. Simon Reidy says:

    What a depressing state of affairs. Apart from One (which relatively speaking has a shit bit-rate as well) there’s almost no chance of seeing any high quality FTA HD in this country, rather we are stuck with a heap of crappy low bit-rate “less than SD” multi-channeling.

    Given I don’t watch any commercial FTA, I’m kind of over it now, but apart from the wastage of bit-rate on audio that you pointed out, the one thing that continues to piss me off to no end, is the fact that ABC1 will continue to be standard def, while their 720p channel is wasted on up scaling SD news to 720p on ABC24! We are missing out on so much cool BBC HD material as a result.

    My only hope is that when the analogue switch off is complete, that they will reverse that situation so hat ABC1 ends ups 720p with ABC24 becoming a 576i channel. However even then, for this to happen everyone out there who wants to watch ABC would need an HD STB, not one of the many useless SD STBs which were sold for so long.

    ABC and SBS are the only channels I care about and both of them provide zero native HD content. It’s a very depressing system that we’ll be stuck with for ages. Bring on the NBN and the IPTV revolution. It’s now our only hope for quality HD programming.

  2. Hi Simon. Some content on One does look really nice. Or, at the least, much better than SD. They used to put the F1 on One pretty much live, and that was a treat. But now One is being redirected from sports to entertainment, so the HD F1 now appears an evening or two later, quite late at night. Still looks nice though.

    The worst misuse of spectrum is SBS, which simply repeats SBS1 on SBS HD, upscaled to 720p. Poorly much of the time. My sense is that occasionally there may be a movie which is higher res on HD than on 1, but I haven’t taken any steps to try to confirm my impression.

    I’m reserving judgement on IPTV. At the moment things like Bigpond Movies are low bitrate. 1.8Mbps, I think, for the SD content. Sometimes it can look respectable, but that’s about it. The codecs are more advanced than MPEG2, allowing somewhat better picture quality. I have watched a couple of so-called HD movies on Bigpond, too, and they are also clearly low bitrate. Some had also had shoddy frame rate conversions, or so it seemed, with a regular jerkiness.

    So no guarantee that IPTV will actually deliver higher quality. I hope I’m wrong though.

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