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.
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.