text stringlengths 1 112 |
|---|
x play |
x pause |
x fast rewind |
x fast forward |
x stop |
table media control point characteristic opcodes for media control |
once the current track starts playing the server should notify the track position |
characteristic to inform clients of the current track position the frequency of notification |
this might seem ridiculous but the longest single video level of concern by the group twenty |
one pilots is days hours minute s and seconds long and it is likely that someone will try |
to break this record |
section mcs and mcp |
is down to th e implementation |
another set of opcodes are available for moving around the current track which are shown |
in table |
opcode name parameters |
x move relative bit signed integer |
x previous segment none |
x next segment none |
x first segment none |
x last segment none |
x goto segment bit signed integer |
table media control point characteristic opcodes for in track movement |
the media control service allows segments to be defined within a track each segment |
includes a name and an absolute offset from the start of the track the commands in table |
allow a move to a specific segment of the current track none of these allow movement |
outside the current track if the parameter value results in moving outside the current track |
then the result will be limited to moving the position to the start of the track or the end of the |
track but the track remains the current track |
issuing the stop command will result in the current track becoming invalid so before any of |
the comma nds in table can be used again the user will need to select another track as |
current |
two further sets of opcodes allow a different track to be selected as the curr ent track |
move within a group move to another group |
opcode name parameters opcode name parameters |
x previous |
track none x previous |
group none |
x next track none x next group none |
x first track none x first group none |
x last track none x last group none |
x goto track bit signed |
int x goto group bit signed |
int |
table media control point opcodes for moving around tracks and groups |
when another group is selected the first track of the current group resulting from the |
command becomes the current track |
chapter telephony and media control |
all segments tracks and groups start numbering at zero where a goto operation is used a |
positive value n is equivalent to going to the first item and then executing the next item |
opcode n times a negative value is equivalent to going to the last item and executing the |
previous item opcode n times |
moving to a new track makes it current and places it in the paused state of the state machine |
of figure |
it is only mandatory to support a minimum of one of the opcodes in the media control point |
characteristic it is unlikely that any implementation would be that spartan but client s can |
check what the server supports by reading the media control point opcodes supported |
characteristic this is a bitfield which indicates which opcodes the server supports |
as always with control point opcodes a client writes the opcode and receives a notificati on |
of the operation in the media control point characteristic with a resultcode indicating |
success opcode not supported or media player inactive once the server has fulfilled the |
request it will also notify the appropriate characteristic for that ope ration if a change has |
occurred in its value |
modifying playback |
the media control service has a couple of neat features for modifying playback and seeking |
the first of these is the ability to request a change in playback speed using the playback speed |
characteristic this can be written by the client to request that the current track is played |
faster or slower the parameter for the characteristic is an bit signed integer p which |
ranges in value from to where the actual p layback speed requested is |
𝑠𝑝𝑒𝑒𝑑𝑝 |
ie the speed is to the power of p this gives a range of to which is |
effectively ¼ to times the standard speed |
playback speed is a blind request the client do es not know whether or not the value of p is |
supported after the request the server notifies the value which has been set in the playback |
speed characteristic if the request was outside the range that the server supports it should |
set it to the clo sest available speed if the media source is live or streamed then the playback |
speed characteristic value may be fixed to a value of it is entirely up to the implementation |
to decide how to adjust the speed and whether to maintain the pitch of the a udio data |
the other characteristic which can be varied is the seeking speed by writing a signed integer |
value to the seeking speed characteristic this is used as a multiple of the current playback |
speed with positive values signifying fast forward and negative values fast reverse the |
seeking speed value is applied to the current playback speed not the default playback speed |
where the value of p would be a value of for the seeking speed indicates a seeking speed |
section mcs and mcp |
which is the same as a playback speed with a value of p regardless of the current playback |
speed |
during seeking the track position characteristic should be notified to provide an indication |
of the current track position the frequency of notification is determined by the |
imple mentation seeking will stop when the track position has reached the start or end of |
the current track |
whilst seeking mcs states that no audio data should be played however the context type |
which describes the use case not the content of the audio stream would not normally |
change |
playing order |
the last feature to cover in mcs is the playing order the playing order characteristic |
provides ten different ways to play tracks most of them cover the order of play when youre |
playing an entire group the options are listed in table |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.