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I am using Flex and FMS to develop a video conferencing application. The technology has helped me tremendously and so far so good. I am using DynamicStream to automatically switch incoming streams to the appropriate bitrate depending on the available bandwidth. I was wondering if there is anyway in which I can instruct the DynamicStream to allow more bandwidth for audio (obviously at the cost of losing some frames from the video).

Any help is appreciated.

Kros
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    +1; this is an advanced question, clearly defined. Although beyond my knowledge. Hopefully someone else can chime in. – JeffryHouser Jul 12 '11 at 17:16
  • Could you show the code you're using? – J_A_X Jul 12 '11 at 17:22
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    http://help.adobe.com/fr_FR/FlashPlatform/reference/actionscript/3/fl/video/DynamicStreamItem.html Looks like it doesn't really know what the audio/video encodings are behind the scenes, according to the docs it doesn't look at the file to determine bitrate but only at the number you pass it, so it seems you could encode the audio at higher fidelity and the video at lower and end up at the same bit rate (or even tell it you did even if you didn't) and it would switch to the appropriate stream, it seems it would have to be configuration on the encoder – shaunhusain Jul 13 '11 at 05:22
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    What are you using to stream in multi bitrate? That DynamicStream class doesn't give you too much opportunity to customize it, at least that is my experience. By the way, lot of unwanted switching down happened, however the bandwidth was excellent. Is this also happened with your app? Honestly this class a little bit confusing me. – Tamas Gronas Jul 19 '11 at 09:04
  • Hi all, yes I am using the DynamicStream class. After carefully examing the problem I am realising that the problem is not the DynamicStream after all. The problem seems to be related to when the 3rd participant joins in. I notice significant lag, echos and sometimes even poor audio quality, especially if 2 or more participants talk at the same time. – Kros Jul 21 '11 at 20:33

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In general I think this is a bad idea, you should start the stream at an acceptable audio bit rate and stick with it, shifting video is tolerable on the eyes for whatever reason, shifting audio bitrates on the fly however is very noticeable and causes quite shift. For a video confrence using mono channel encoded audio at a decent bitrate is going to take up about 1% of the data in comparison to the video, this is why it's not even really controllable, it just dosen't make sense, and is a bad end user experience. A good way to test this is take a video of someone talking, encode sections of the audio at different bit rates and splice the hole thing back together.... notice the jarring during the shift. For whatever reason the human brain responds drastically different to shifts in audio quality versus shifts in video quality... perhaps it's because although we may not always be able to see everything around us, we can always hear it. Either way your much better off spending your time where it counts: video! Just my $.02

JTtheGeek
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  • thank for the info JTtheGeek. Will try it out once I get back to working on that project. – Kros Aug 24 '11 at 15:22