Freeview Update: 7flix launches 28th February

Channel 7 had been teasing us with a New Channel Coming Soon since some-time in December last year, and speculation went wild as to what might happen. Many ideas were floated by various online forum members, no least, in Austech where they claimed to have exclusive leaks of information which were entirely unsourced. While I had set up some equipment to monitor the multiplex, I was entirely disheartened to see that it didn’t have anything “new” to speak of throughout the Australian Open, and again by Feb 1 which was an important date judging from their promos.

Thanks to Mr. Nugent for tipping me off this morning that something actually did come up on the slot – it is now known as 7flix and will launch 28th Feburary. At the present moment, the channel is running the following promotional loop:

Of course, this has impacted on the channel table and bit-rates which I measured from a one-hour TS capture (owing to a lack of time).

Ch7-ProgramTable

Due to a change of software, I am not able to ascertain the mode (stereo or parametric-stereo) of the LATM encapsulated MPEG-4 audio, but significant changes include the move of TV4ME to use both MPEG-4 video and audio to save some bit-rate, and the change of the main 7 Digital audio to be in Joint-Stereo mode for better efficiency and quality although possibly at the expense of stereo imaging.

Ch7-bitrate-evolution

The bitrate evolution-over-time chart shows that the bit-rates of the channels do jump around a bit. In November 2015, they were broadcasting a large number of null packets, which was corrected in January 2016 by giving most of it to 7mate. The New Channel placeholder used a minimal bit-rate, but now, as there is a promo being run, the bit-rate has been increased. The savings from MPEG-4 conversion of TV4ME is still relatively limited, but is a welcome contribution to the other channels.

At the present moment, this is unlikely to be their final configuration. The reason I say this is because the null packet rate is still above 1Mbit/s:

Ch7-Bitrate-BreakdownIt seems likely that there is about 800kbit/s of null padding which may be safely taken and allocated to a service, which may actually happen when real programs start being run on the channel.

ch7-statmuxing

While checking the bit-rates of the channels, I noticed that stat-muxing seems to be switched on for Channel 7 now. Previously, their bit-rates were very “solid” and fixed, with manual changes for certain events and programs. Now there is a slight “bow” to some services while others remain “clamped” at a particular bit-rate. As a result, it seems there has been some behind-the-scenes changes to their encoder configuration during this period.

Of course, the users which still have older TV sets with integrated tuners, or standalone HD Set-top-Boxes before H.264 and AAC-HEv2 were implemented will find they cannot receive TV4ME, 7flix or RACING.COM as they all use the same sets of codecs which were not part of the initial DVB-T standard. At least the main channels remain accessible, but no HD simulcast is yet available.

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4 Responses to Freeview Update: 7flix launches 28th February

  1. Ian Nugent says:

    Hi, thanks for doing that so fast. Very interesting results. I have heard that some people got 4:3 when watching TV4ME, I wonder if some decoders can’t handle the 480×576.

    • lui_gough says:

      I think it may just be a result of their TV not obeying the display-aspect-ratio tagging on the stream itself, as there are a variety of horizontal resolutions which are legal for DVB-T and are supposed to be stretched to either 4:3 or 16:9 depending on the DAR flags.

      According to MediaInfo, the DAR is correctly set at 16:9.
      Video
      ID : 625 (0x271)
      Format : AVC
      Format/Info : Advanced Video Codec
      Format profile : [email protected]
      Format settings, CABAC : Yes
      Format settings, ReFrames : 4 frames
      Bit rate : 1 029 Kbps
      Width : 480 pixels
      Height : 576 pixels
      Display aspect ratio : 16:9
      Frame rate : 25.000 fps
      Color space : YUV
      Chroma subsampling : 4:2:0
      Bit depth : 8 bits
      Scan type : MBAFF
      Scan order : Top Field First
      Bits/(Pixel*Frame) : 0.149
      Color range : Limited
      Color primaries : BT.601 PAL
      Transfer characteristics : BT.470 System B, BT.470 System G
      Matrix coefficients : BT.601

      – Gough

  2. Michael Lee says:

    7flix sound really noisy, 4me sound really noisy racing.com sound really noisy

    • lui_gough says:

      Noisy as in you are receiving just white noise? Or noisy as in the quality is low and the audio is murky?

      If it’s the former, then your decoder is not compatible with AAC-HEv2 which is used in the broadcast, as this codec was NOT part of the DVB-T standard (and neither was MPEG-4 H.264 AVC). You will need to use either a PC based tuner or a new set-top box compatible with MPEG-4 audio. Other people in this situation may find no audio at all, but they may have video, or both no audio and no video.

      If it’s the latter, it’s to be expected as the bitrate of the audio on these channels are well reduced to levels similar to and below that of digital radio.

      – Gough

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