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Memory leak in TVService
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<blockquote data-quote="CyberSimian" data-source="post: 1285829" data-attributes="member: 141969"><p>For the DVB EPG, TV Server makes available various settings that provide a great deal of flexibility. This is partly to satisfy users' different needs, and partly to accommodate the different EPG arrangements used by different countries around the world. But the result is that there is a great deal of scope for picking a combination of settings that is not optimal. Below I suggest settings for DVB-T/T2 in the UK. For other countries, the considerations will be similar, but the details may not be identical.</p><p></p><p><strong>Overview</strong></p><p>The broadcast EPG can be regarded as a carousel that rotates continuously. To obtain a complete 7-day EPG, TV Server needs to grab the EPG for one complete rotation of the carousel. When digital TV started in the UK, one rotation took around 4 minutes, but with the explosion in the number of channels, one rotation nowadays take around 8 to 10 minutes. The exact time needed varies from day to day (depending on the content of the EPG), so it can take less than 8 minutes or more than 10 minutes. It will also depend on where you are in the UK. Some locations may receive fewer channels, and so have a smaller EPG.</p><p></p><p>Because TVs mostly do not store the EPG across standby, the programme info for the next several hours needs to be repeated in the broadcast EPG every few seconds. This is so that the user can see what is on in the near future without having to wait several minutes for the EPG to populate. On the other hand, those programmes which occur 7 days in the future are likely to occur only once in the carousel. Consequently, if you grab the EPG for only 2 minutes, you are unlikely to receive the programme info for all of the programmes that are 6 to 7 days in the future. You may notice this by finding that there are gaps in the MP EPG for 6 to 7 days in the future. These gaps will populate as the days pass, but of course the gaps are inconvenient of you want to schedule a programme to record that is 7 days in the future but not yet present in the MP EPG.</p><p></p><p><strong>Idle EPG grabber</strong></p><p>For the idle EPG grabber, the grab duration specified is the maximum time TV Server will operate a tuner and extract the EPG from the datastream. However, TV Server is able to determine when it has seen one complete rotation of the carousel, and stop grabbing . So you could specify a grab duration of 60 minutes, but TV Server would still grab only for 8 to 10 minutes.</p><p></p><p>The grabbing phase extracts the programme info from the broadcast datastream, and caches it in RAM (at least, I think that is how it works). After grabbing is complete, database update starts. The duration of database update will depend on the speed of your hard disk. I use a slowish Western Digital Green drive for Windows, and the database update phase takes longer than the grabbing phase: 8 to 10 minutes for grabbing, 15 to 20 minutes for database update.</p><p></p><p>To ensure that you always have a full EPG (no gaps), I would recommend performing one idle grab each day, with a grab duration of 15 minutes (for the UK). You can use "PowerScheduler" to cause your HTPC to wake at a time when your HTPC is not in use, grab the EPG, and then return to sleep. I would suggest a refresh time that is 24 hours or just under. A refresh time of 24 hours will stop the idle grabber running during the day when you don't want it to run.</p><p></p><p><strong>Timeshift EPG grabber</strong></p><p>If you use the timeshift grabber, you need to understand a difference between the MUXes. In the UK, each MUX broadcasts the EPG for its own channels, plus the EPGs for all of the other MUXes. However, each MUX transmits differently-ordered data. The best MUXes to use for grabbing are the "BBC1 SD" MUX and the "BBC1 HD" MUX. These MUXes treat the different channels equally, and do not favour the BBC channels unduly. In contrast, the non-BBC MUXes favour their own channels. So if you use only the timeshift grabber, and mostly watch channels which are not in the BBC MUXes, you are likely once again to find gaps in the EPG.</p><p></p><p>The timeshift grabber is useful for receiving last-minute changes in the EPG (for example, when live sport overruns, or news broadcasts are extended due to world events). But you only need to run the timeshift grabber for a short time, to receive programme info for the next hour or two. A grab time of 1 to 2 minutes is appropriate for this. However, there is a "gotcha"...</p><p></p><p><strong>Settings with undesirable side effects</strong></p><p>I don't understand the details of the TV Server implementation, but there are two settings that can have undesirable consequences:</p><p></p><p>(1) Grab EPG only for channels on the same transponder</p><p>(2) Store data only for selected channels</p><p></p><p>If neither (1) nor (2) is enabled, TV Server can grab the entire EPG from a single MUX (transponder) in one pass.</p><p></p><p>If (1) is enabled, TV Server needs to tune each MUX in turn. So at my location where I can receive 6 MUXes, EPG grabbing using the idle grabber would take around 6 times longer.</p><p></p><p>If (2) is enabled, TV Server tunes each selected channel in turn in order to grab its EPG. So at my location with around 80 channels enabled, EPG grabbing using the idle grabber would take around 80 times longer.</p><p></p><p>Because of (1) and (2), the recommendation is to select <strong>only one channel</strong> for grabbing. The "gotcha" is that if you select only one channel for grabbing, the timeshift grabber will work only when you watch or record that channel -- it won't run when watching/recording any other channel.</p><p></p><p><strong>Settings that I use</strong></p><p>In the 7 years that I have been using MP, my EPG settings have evolved several times. Conceptually I use the idle grabber once each day (at 06:00 hours), and don't use the timeshift grabber. But in practice I actually do this:</p><p></p><p>(1) Disable the idle grabber.</p><p>(2) Enable the timeshift grabber, with one channel in the BBC MUX selected.</p><p>(3) Record that channel at 06:00 hours for 40 minutes each day.</p><p></p><p>This gives me a complete EPG grab each day, but allows me to receive last-minute changes to the EPG by recording or watching that channel for 1 to 2 minutes at any time during the day (although I don't often do this). The channel that I use is a BBC radio channel, but a BBC TV channel is equally good. Another advantage of using the timeshift grabber is that the grab still occurs, even if a recording is taking place at the scheduled grab time (the idle grabber would be prevented from running if a recording was occurring or live TV being viewed).</p><p></p><p> My settings are shown below. Notice that <strong>no channels</strong> are selected on the "TV EPG Grabber" panel, and <strong>one channel</strong> is selected on the "Radio EPG Grabber" panel:</p><p></p><p>[ATTACH]209162[/ATTACH] [ATTACH]209163[/ATTACH] [ATTACH]209164[/ATTACH]</p><p></p><p><strong>Memory leak</strong></p><p>With the different EPG settings that I have used over the years, I have not encountered the memory leak. But then I have never used the "record every time on every channel" option. So at the moment it looks to me that that option is the culprit (but I have not tested this yet).</p><p></p><p>-- from CyberSimian in the UK</p></blockquote><p></p>
[QUOTE="CyberSimian, post: 1285829, member: 141969"] For the DVB EPG, TV Server makes available various settings that provide a great deal of flexibility. This is partly to satisfy users' different needs, and partly to accommodate the different EPG arrangements used by different countries around the world. But the result is that there is a great deal of scope for picking a combination of settings that is not optimal. Below I suggest settings for DVB-T/T2 in the UK. For other countries, the considerations will be similar, but the details may not be identical. [B]Overview[/B] The broadcast EPG can be regarded as a carousel that rotates continuously. To obtain a complete 7-day EPG, TV Server needs to grab the EPG for one complete rotation of the carousel. When digital TV started in the UK, one rotation took around 4 minutes, but with the explosion in the number of channels, one rotation nowadays take around 8 to 10 minutes. The exact time needed varies from day to day (depending on the content of the EPG), so it can take less than 8 minutes or more than 10 minutes. It will also depend on where you are in the UK. Some locations may receive fewer channels, and so have a smaller EPG. Because TVs mostly do not store the EPG across standby, the programme info for the next several hours needs to be repeated in the broadcast EPG every few seconds. This is so that the user can see what is on in the near future without having to wait several minutes for the EPG to populate. On the other hand, those programmes which occur 7 days in the future are likely to occur only once in the carousel. Consequently, if you grab the EPG for only 2 minutes, you are unlikely to receive the programme info for all of the programmes that are 6 to 7 days in the future. You may notice this by finding that there are gaps in the MP EPG for 6 to 7 days in the future. These gaps will populate as the days pass, but of course the gaps are inconvenient of you want to schedule a programme to record that is 7 days in the future but not yet present in the MP EPG. [B]Idle EPG grabber[/B] For the idle EPG grabber, the grab duration specified is the maximum time TV Server will operate a tuner and extract the EPG from the datastream. However, TV Server is able to determine when it has seen one complete rotation of the carousel, and stop grabbing . So you could specify a grab duration of 60 minutes, but TV Server would still grab only for 8 to 10 minutes. The grabbing phase extracts the programme info from the broadcast datastream, and caches it in RAM (at least, I think that is how it works). After grabbing is complete, database update starts. The duration of database update will depend on the speed of your hard disk. I use a slowish Western Digital Green drive for Windows, and the database update phase takes longer than the grabbing phase: 8 to 10 minutes for grabbing, 15 to 20 minutes for database update. To ensure that you always have a full EPG (no gaps), I would recommend performing one idle grab each day, with a grab duration of 15 minutes (for the UK). You can use "PowerScheduler" to cause your HTPC to wake at a time when your HTPC is not in use, grab the EPG, and then return to sleep. I would suggest a refresh time that is 24 hours or just under. A refresh time of 24 hours will stop the idle grabber running during the day when you don't want it to run. [B]Timeshift EPG grabber[/B] If you use the timeshift grabber, you need to understand a difference between the MUXes. In the UK, each MUX broadcasts the EPG for its own channels, plus the EPGs for all of the other MUXes. However, each MUX transmits differently-ordered data. The best MUXes to use for grabbing are the "BBC1 SD" MUX and the "BBC1 HD" MUX. These MUXes treat the different channels equally, and do not favour the BBC channels unduly. In contrast, the non-BBC MUXes favour their own channels. So if you use only the timeshift grabber, and mostly watch channels which are not in the BBC MUXes, you are likely once again to find gaps in the EPG. The timeshift grabber is useful for receiving last-minute changes in the EPG (for example, when live sport overruns, or news broadcasts are extended due to world events). But you only need to run the timeshift grabber for a short time, to receive programme info for the next hour or two. A grab time of 1 to 2 minutes is appropriate for this. However, there is a "gotcha"... [B]Settings with undesirable side effects[/B] I don't understand the details of the TV Server implementation, but there are two settings that can have undesirable consequences: (1) Grab EPG only for channels on the same transponder (2) Store data only for selected channels If neither (1) nor (2) is enabled, TV Server can grab the entire EPG from a single MUX (transponder) in one pass. If (1) is enabled, TV Server needs to tune each MUX in turn. So at my location where I can receive 6 MUXes, EPG grabbing using the idle grabber would take around 6 times longer. If (2) is enabled, TV Server tunes each selected channel in turn in order to grab its EPG. So at my location with around 80 channels enabled, EPG grabbing using the idle grabber would take around 80 times longer. Because of (1) and (2), the recommendation is to select [B]only one channel[/B] for grabbing. The "gotcha" is that if you select only one channel for grabbing, the timeshift grabber will work only when you watch or record that channel -- it won't run when watching/recording any other channel. [B]Settings that I use[/B] In the 7 years that I have been using MP, my EPG settings have evolved several times. Conceptually I use the idle grabber once each day (at 06:00 hours), and don't use the timeshift grabber. But in practice I actually do this: (1) Disable the idle grabber. (2) Enable the timeshift grabber, with one channel in the BBC MUX selected. (3) Record that channel at 06:00 hours for 40 minutes each day. This gives me a complete EPG grab each day, but allows me to receive last-minute changes to the EPG by recording or watching that channel for 1 to 2 minutes at any time during the day (although I don't often do this). The channel that I use is a BBC radio channel, but a BBC TV channel is equally good. Another advantage of using the timeshift grabber is that the grab still occurs, even if a recording is taking place at the scheduled grab time (the idle grabber would be prevented from running if a recording was occurring or live TV being viewed). My settings are shown below. Notice that [B]no channels[/B] are selected on the "TV EPG Grabber" panel, and [B]one channel[/B] is selected on the "Radio EPG Grabber" panel: [ATTACH alt="dvb_epg.jpg"]209162[/ATTACH] [ATTACH alt="tv_epg_grabber.jpg"]209163[/ATTACH] [ATTACH alt="radio_epg_grabber.jpg"]209164[/ATTACH] [B]Memory leak[/B] With the different EPG settings that I have used over the years, I have not encountered the memory leak. But then I have never used the "record every time on every channel" option. So at the moment it looks to me that that option is the culprit (but I have not tested this yet). -- from CyberSimian in the UK [/QUOTE]
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