The BBC have further reduced the bitrate from about 7Mbps see Episode of Dr Who
General
ID : 1 (0x1)
Complete name : E:\DrWho\Doctor Who_Ep01.ts
Format : BDAV
Format/Info : Blu-ray Video
File size : 1.41 GiB
Duration : 47mn 39s
Overall bit rate mode : Variable
Overall bit rate : 4 247 Kbps
Video
ID : 5400 (0x1518)
Menu ID : 6941 (0x1B1D)
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4
Format settings, CABAC : Yes
Format settings, ReFrames : 4 frames
Codec ID : 27
Duration : 47mn 39s
Bit rate : 3 424 Kbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate : 25.000 fps
Standard : Component
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : MBAFF
Scan order : Top Field First
Bits/(Pixel*Frame) : 0.066
Stream size : 1.14 GiB (81%)
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
Audio #1
ID : 5401 (0x1519)
Menu ID : 6941 (0x1B1D)
Format : AC-3
Format/Info : Audio Coding 3
Mode extension : CM (complete main)
Format settings, Endianness : Big
Codec ID : 6
Duration : 47mn 39s
Bit rate mode : Constant
Bit rate : 384 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Compression mode : Lossy
Delay relative to video : -1s 34ms
Stream size : 131 MiB (9%)
Language : English
Audio #2
ID : 5402 (0x151A)
Menu ID : 6941 (0x1B1D)
Format : MPEG Audio
Format version : Version 1
Format profile : Layer 2
Codec ID : 3
Duration : 47mn 39s
Bit rate mode : Constant
Bit rate : 256 Kbps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Compression mode : Lossy
Delay relative to video : -1s 2ms
Stream size : 87.3 MiB (6%)
Language : nar
Text #1
ID : 5403 (0x151B)-888
Menu ID : 6941 (0x1B1D)
Format : Teletext
Language : English
Text #2
ID : 5404 (0x151C)
Menu ID : 6941 (0x1B1D)
Format : DVB Subtitle
Codec ID : 6
Duration : 47mn 35s
Delay relative to video : 4s 485ms
Language : English