Bitrate mismatch when creating video files in 720p and 1080p

To benefit from adaptive bitrate streaming over HTTP, I have created a file in different bitrates and screen sizes, when I created files in 144p , 240p , 360p and 480p the switching between videos happened, by decreasing the bandwidth the player switched to the video with lower bitrate and by increasing the bandwidth the player switched to the video with higher bitrate.

Question 1: But sometimes the video was switched to different lower or higher bitrates without any decrease or increase in bandwidth. How can I cure it?

Question 2: When I created files in 720p and 1080p the player only played the video file of 144p without switching to the videos with higher bitrates and kept buffering during the play back of video file of 144p. What should I do to make the player to switch to videos with higher bitrates when the bandwidth is increased properly?

ffmpeg -re -i j:\movie\need4speed.mp4

-preset ultrafast -threads 1 -vcodec libx264 -b:v 3000k -r 24 -g 24 -keyint_min 4 -x264opts "keyint=4:min-keyint=48:no-scenecut" -s 2566*1080 -acodec libvo_aacenc -b:a 16k -ac 1 -ar 8000 -f flv rtmp://10.1.1.1/livepkgr/need4speed1080p?adbe-live-event=liveevent

-preset ultrafast -threads 1 -vcodec libx264 -b:v 2048k -r 24 -g 24 -keyint_min 4 -x264opts "keyint=4:min-keyint=48:no-scenecut" -s 1710*720 -acodec libvo_aacenc -b:a 16k -ac 1 -ar 8000 -f flv rtmp://10.1.1.1/livepkgr/need4speed720p?adbe-live-event=liveevent

-preset ultrafast -threads 1 -vcodec libx264 -b:v 1024k -r 24 -g 24 -keyint_min 4 -x264opts "keyint=4:min-keyint=48:no-scenecut" -s 1140*480 -acodec libvo_aacenc -b:a 16k -ac 1 -ar 8000 -f flv rtmp://10.1.1.1/livepkgr/need4speed480p?adbe-live-event=liveevent

-preset ultrafast -threads 1 -vcodec libx264 -b:v 600k -r 24 -g 24 -keyint_min 4 -x264opts "keyint=4:min-keyint=48:no-scenecut" -s 856*360 -acodec libvo_aacenc -b:a 16k -ac 1 -ar 8000 -f flv rtmp://10.1.1.1/livepkgr/need4speed360p?adbe-live-event=liveevent

-preset ultrafast -threads 1 -vcodec libx264 -b:v 350k -r 24 -g 24 -keyint_min 4 -x264opts "keyint=4:min-keyint=48:no-scenecut" -s 570*240 -acodec libvo_aacenc -b:a 16k -ac 1 -ar 8000 -f flv rtmp://10.1.1.1/livepkgr/need4speed240p?adbe-live-event=liveevent

-preset ultrafast -threads 1 -vcodec libx264 -b:v 128k -r 24 -g 24 -keyint_min 4 -x264opts "keyint=4:min-keyint=48:no-scenecut" -s 342*144 -acodec libvo_aacenc -b:a 16k -ac 1 -ar 8000 -f flv rtmp://10.1.1.1/livepkgr/need4speed144p?adbe-live-event=liveevent

<manifest xmlns="http://ns.adobe.com/f4m/2.0">

<dvrInfo beginOffset="0" endOffset="1800"></dvrInfo>

<baseURL>http://10.1.1.1/hds-live/livepkgr/_definst_/liveevent</baseURL>

<media href="need4speed144p.f4m" bitrate="200"/>

<media href="need4speed240p.f4m" bitrate="512"/>

<media href="need4speed360p.f4m" bitrate="720"/>

<media href="need4speed480p.f4m" bitrate="1600"/>

<media href="need4speed720p.f4m" bitrate="2200"/>

<media href="need4speed1080p.f4m" bitrate="3500"/>

</manifest>

Please advise me on the above two matters.

Thanks

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