IPlayer TV
From Beebhack
Contents |
[edit] General technical overview
[edit] Programme IDs
All programme episodes on BBC TV are assigned a programme ID (PID) made up of lower-case letter and numbers of around 8 characters. More information on the format of the PID's can be found at the BBC Programme Guide. For Instance for Torchwood, you can see which programmes are available on iPlayer.
In addition to this, it is possible for episodes in iPlayer to have several published "versions". Every episode of a programme should have at least one version - the "original". Other versions that exist are:
| version_type_id | name |
|---|---|
| AudioDescribed | Audio description |
| Lengthened | Lengthened |
| OpenSubtitled | Open subtitles |
| Original | Original version |
| Other | Other |
| Shortened | Shortened |
| Signed | Sign language |
| WarningsHigher | Stronger content warnings |
| WarningsLower | Milder content warnings |
| WarningsNone | No content warnings |
[edit] Retrieving programme meta-data
See IPlayer_Metadata
[edit] Subtitles
Subtitles are available on some iPlayer programmes. The subtitles are in W3C Timed-Text format. The S button on the Flash based iPlayer makes use of this file. The URL for a specific subtitle feed is determined by obtaining the 'version pid' for the programme. Retrieving programme media stream information as described above. It will have a stanza with something like:
<media kind="captions"
type="application/ttaf+xml" >
<connection
priority="10"
kind="http"
server="http://www.bbc.co.uk/iplayer/subtitles/"
identifier="b0008dc8rstreaming89808204.xml"
href="http://www.bbc.co.uk/iplayer/subtitles/b0008dc8rstreaming89808204.xml"
/>
</media>
The subtitle feed can be downloaded from the URL pointed to in the href field, e.g.: http://www.bbc.co.uk/iplayer/subtitles/b0008dc8rstreaming89808204.xml
[edit] Scripts and programs
See Programs
[edit] Windows P2P Version
See Windows P2P
[edit] Flash / RTMP Version
See Flash iPlayer
[edit] iPhone Version
[edit] Nintendo Wii Flash Version
See Nintendo Wii
[edit] Nokia N96 / RTSP Version
[edit] Note about technical image quality
Please note: the technical image quality varies widely across the different versions of iPlayer output, particularly between the DRM-enabled version for Windows, and the iPhone version. Taking one program as an example, "House of Saddam" episode 1, broadcast on Wed 30th July 2008, the compression details are as follows (iphone and Windows DRM versions only were compared):
[edit] Comparison Table
| Reception Method | Access Method | Video Codec | Video Resolution | Video Bitrate | Video Quality | Audio Codec | Audio Bitrate | Overall Bitrate |
| Windows WMV DRM | Kontiki p2p | WMV 9 | 672 x 544 | 475 kbps | VHS | WMA 9.1 | 128 kbps | 608 kbps |
| Mobile WMV DRM | HTTP download | WMV 9 | 320 x 176 | 475 kbps | VHS | WMA9.1 | 128 kbps | 608 kbps |
| iPhone | HTTP download | H.264 | 483 x 272 | 400 kbps | Below VHS | AAC | 112 kbps | 512 kbps |
| Nokia N95 Wifi | RTSP streaming | H.264 | 320 x 176 | 128 kbps | Well Below VHS | AAC | 64 kbps | 192 kbps |
| Nokia N95 3G | RTSP streaming | H.264 | 176 x 96 | 80 kbps | Very Low | AAC | 32 kbps | 113 kbps |
| Flash (standard quality) | RTMP streaming | On2 VP6 | 512 x 288 | 372 kbps | Below VHS | MP3 44kHz CBR | 128 kbps | 500 kbps |
| Flash (high quality) | RTMP streaming | H.264 | 640 x 360 | 704 kbps | Near VHS | AAC+ | 96 kbps | 800 kbps |
| Nintendo Wii Flash | RTMP streaming | Sorenson Spark | 512 x 288 | Below VHS | 820 kbps | |||
| Flash (very high quality) | RTMP streaming | H.264 | 832 x 468 | 1404 kbps | better than VHS | AAC+ | 96 kbps | 1500 kbps |
| Flash (HD 720p quality) | RTMP streaming | H.264 | 1280 x 720 | 3072 kbps | better than DVD | AAC | 128 kbps | 3200 kbps |
