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Thread: Reduced ABC bandwidth to barely squintable

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    Default Reduced ABC bandwidth to barely squintable

    Since some time after the introduction of ABC HD I have noticed that all of the Sydney ABC channels now have severely reduced bandwidth.

    Before ABC HD we had these approximate actual bitrates:

    ABC News: 7.0Mbps
    ABC1: 4.8Mbps
    ABC2: 3.8Mbps
    ABC3: 4.3Mbps

    Now we have:

    ABC HD: 3.2Mbps
    ABC News 24: 3.3Mbps
    ABC1: 2.0Mbps
    ABC2: 2.8Mbps
    ABC3: 2.6Mbps

    It is as though the ABC have reduced the net bandwidth for frequency 226.5MHz from 20Mbps to just 14.0Mbps.
    And as a result ABC1 is barely viewable now.

    One would have through that ABC News 24 (HD) would have simply split into one 3.5Mbps MPEG4 channel plus one 3.5Mbps MPEG2 channel.
    Instead every other channel has halved in bandwidth as well.
    Maybe somebody has made a simple mistake?

    Has anybody else noticed this?
    Last edited by nhfgrpu; 11-01-17 at 03:09 PM.



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    This is a problem you may be the only one experiencing it due to a problem existing in either your TV or from the antenna to the TV.
    While I am not doubting things have changed as you have stated but if ABC1 is as bad as say, its a wonder there hasnt been comments made by other viewers.

    Going on the numerous complaints posted regarding the reception of SBS as Digital TV was being introduced and those who had problems receiving ALL of each channel, ie you could get 7TWO but not 7MATE, these changes to the ABC's transmission MAY be causing the poor 'quality' of the picture for you.

    I just checked my ABC line up and it looks pretty normal to me (both are showing a speech by outgoing US President Obama) but I am not getting my reception from Sydney but a regional Translator.
    I stand unequivicably behind everything I say , I just dont ever remember saying it !!

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    Quote Originally Posted by gordon_s1942 View Post
    This is a problem you may be the only one experiencing it due to a problem existing in either your TV or from the antenna to the TV.
    While I am not doubting things have changed as you have stated but if ABC1 is as bad as say, its a wonder there hasnt been comments made by other viewers.
    Well, since I am getting a respectable 6.6Mbps from 7 HD (mpeg4), and 4.0Mbps from 9HD (mpeg4), and 4.5Mbps from 9 (mpeg2 SD), and 7.7Mbps from SBS HD, I don't think there is a problem with my antenna. Also this is about Sydney transmission on 226.5MHz and not some regional transmitter.

    Besides, this all started with the advent of ABC HD. And my antenna hasn't changed. And if my antenna was somehow faulty then I reckon I would see a large number of errors since any bandwidth crimping problem would show up as bit errors. Also the ABC1 picture does look quite fuzzy and no antenna problem can do that to a digital signal.

    Why am I the only person to complain? Because somebody has to be first. And it is often me. Besides, who else has the ability to measure that ACTUAL bitrate of a DVB signal and not just the NIT bandwidth (which is still published in ABC1 NIT as being 7Mhz, with PES video bitrate declared to be 6Mbps).
    Last edited by nhfgrpu; 11-01-17 at 03:51 PM.

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    I follow your posting quite clearly and am aware your posting was in relation to that received from the Sydney based ABC transmitter at Gore Hill.
    You obviously have some technical expertise to be able to measure the bandwith and other details which I have no clue what so ever about.
    Other reasons there have been no other complaints your aware of is that its only affecting you and you dont think thats likely then the other reason is that so many may mumble, mutter and whinge when a signal plays up, many will either just change channels or wait for it to improve no matter how long it takes.

    My posting was basically suggesting that you check around if possible to see if this problem is affecting others and if it is, it would prevent the channel from simply dismissing any complaints made to them about their transmission when it comes from a number of viewers rather than just one.
    I stand unequivicably behind everything I say , I just dont ever remember saying it !!

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    Looking at the problem in more detail I can also see a significant change in the composition of the signal.

    Up until recently the ratio of I:B:P frames was something like 1 : 8 : 4
    But currently it has been changed to approximately 1 : 22 : 10

    This is not necessarily the cause of the low bitrate because a channel such as Channel 7 manages to achieve a bitrate of 4.0Mbps with a 1 : 16 : 7 ratio.
    But it does indicate that a significant change in equipment or configuration has occurred recently.
    Last edited by nhfgrpu; 16-01-17 at 10:55 AM. Reason: Unwanted icons appearing

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    If your not one already (Amateur), have you thought of asking any of the Amateur Radio operators, particularly those who do the Amateur TV as I read one time some of their members worked in the industry and may even work at the ABC itself to find out why your getting the readings you are.
    I stand unequivicably behind everything I say , I just dont ever remember saying it !!

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    Quote Originally Posted by gordon_s1942 View Post
    If your not one already (Amateur), have you thought of asking any of the Amateur Radio operators, particularly those who do the Amateur TV as I read one time some of their members worked in the industry and may even work at the ABC itself to find out why your getting the readings you are.
    Why not suggest that I contact the ABC? That would make a lot more sense.

    Like if my council fails to pick up my rubbish it wouldn't make sense to contact Mercedes Benz just because they have trucks too.

    Incidentally, I have looked back to the date when ABC HD was introduced and shortly after that date the bitrates were:

    ABC HD: 2.8Mbps
    ABC News 24: 3.0Mbps
    ABC1: 4.0Mbps
    ABC2: 1.7Mbps
    ABC3: 3.4Mbps

    give or take a bit (because measurement depends on content somewhat).

    ABC1 appears to have had its bitrate halved some time after 6th Dec, either deliberately or accidentally.
    Last edited by nhfgrpu; 16-01-17 at 11:04 AM.

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    I'd be interested in how you monitor the bit rates and other data from the DTV systems
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    Quote Originally Posted by nhfgrpu View Post
    Why not suggest that I contact the ABC? That would make a lot more sense.

    Like if my council fails to pick up my rubbish it wouldn't make sense to contact Mercedes Benz just because they have trucks too.

    Incidentally, I have looked back to the date when ABC HD was introduced and shortly after that date the bitrates were:

    ABC HD: 2.8Mbps
    ABC News 24: 3.0Mbps
    ABC1: 4.0Mbps
    ABC2: 1.7Mbps
    ABC3: 3.4Mbps

    give or take a bit (because measurement depends on content somewhat).

    ABC1 appears to have had its bitrate halved some time after 6th Dec, either deliberately or accidentally.
    I didnt suggest contacting the ABC it because to try and find anyone to answer your queries might be virtually impossible and even if you did, unless your in a position,/job etc to authorise a reply, you would most likely get the 'everything is within accordance with the broadcasting criteria' so I suggested the other alternative.
    When you buy a new car, you dont just ask the salesman what its like but someone who has driven one.
    Ringing the Council about a Garbage problem may not solve it as most Councils use contractors today so if theres a problem with the collection, they may refer you to them and if its Mercedes Benz who are the contractors for your area, you may well indeed have to call them.
    Last edited by gordon_s1942; 16-01-17 at 01:15 PM.
    I stand unequivicably behind everything I say , I just dont ever remember saying it !!

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    Quote Originally Posted by porkop View Post
    I'd be interested in how you monitor the bit rates and other data from the DTV systems
    My Promax meter displays the bitrate. I' m pretty sure you can also see the bitrate using tsreader.

    Edit tsreader displays lots of info / graphs.

    Last edited by cmatten; 20-01-17 at 10:13 AM.

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    Quote Originally Posted by nhfgrpu View Post
    ABC HD: 2.8Mbps
    ABC News 24: 3.0Mbps
    ABC1: 4.0Mbps
    ABC2: 1.7Mbps
    ABC3: 3.4Mbps

    give or take a bit (because measurement depends on content somewhat).

    ABC1 appears to have had its bitrate halved some time after 6th Dec, either deliberately or accidentally.
    What are you using to measure the bitrate and how long are they averaged over? On my Promax it updates multiple times per second. I'm seeing it vary from 3Mbps to 6Mbps.

    Might see if I can get tsreader going again and make some measurements as the results seem to be averaged out over the measurement period.

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    Quote Originally Posted by cmatten View Post
    What are you using to measure the bitrate and how long are they averaged over?
    It is really really simple. You simply divide the raw bytes by the time. Nothing could be simpler.

    In fact anyone who can record a transport stream can measure this for themselves. Capture for, say, 300 seconds, then multiple the resulting file size by 8 and then divide by 300.

    However I can report that the problem appears to have been partially rectified. I am seeing approx 3.3Mbps on ABC1 now. Not quite the 4Mbps it used to be, but somewhat better that the less than 2Mbps that it was. Noticeably better quality video to look at visually too - not quite as fuzzy.
    Last edited by nhfgrpu; 20-01-17 at 05:27 PM.

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    Quote Originally Posted by nhfgrpu View Post
    Since some time after the introduction of ABC HD I have noticed that all of the Sydney ABC channels now have severely reduced bandwidth.

    Has anybody else noticed this?
    I agree with @nhfgrpu, since intro of ABC20 HD the picture quality is poor even by SD standards. I haven't done a bit rate check but just by simply doing a-b comparison viewing test of the same program on ABC2 SD and ABC20 HD I can see that the SD picture is good and much sharper than HD. BTW I'm watching it on a 46" Panasonic Plasma HD tv.

    So given your tests and my own experience it looks like there is definitely a picture quality issue since the intro of ABC20 HD.

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    Quote Originally Posted by whirler79 View Post
    ... the SD picture is good and much sharper than HD.
    Really? Must be something seriously wrong with your TV if SD at 1.7Mbps is looking better than HD mpeg4 at 3Mbps.

    This thread was really about the totally opposite situation. It was about SD channels having their bitrates halved.

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    I see in the tea leaves a compression standard change coming. Courtesy of the Beerman.
    "the one with the sugar coating is the one that would otherwise taste worst".

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    Quote Originally Posted by beerman View Post
    I see in the tea leaves a compression standard change coming.
    What will that mean for Joe Average TV Viewer?
    If Australia is a democracy why, then, is voting compulsory?

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    I am surprised nobody outside Sydney has made any remarks whatsoever about noticing this effect which makes me wonder is this just occurring there and no Capitol City, Regional or Remote locations?
    I stand unequivicably behind everything I say , I just dont ever remember saying it !!

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