files/en-us/web/api/sourcebuffer/mode/index.md
{{APIRef("Media Source Extensions")}}{{AvailableInWorkers("window_and_dedicated")}}
The mode property of the {{domxref("SourceBuffer")}}
interface controls whether media segments can be appended to the
SourceBuffer in any order, or in a strict sequence.
The two available values are:
segments: The media segment timestamps determine the order in which the
segments are played. The segments can be appended to the SourceBuffer in
any order.sequence: The order in which the segments are appended to the
SourceBuffer determines the order in which they are played. Segment
timestamps are generated automatically for the segments that observe this order.The mode value is initially set when the SourceBuffer is created using
MediaSource.addSourceBuffer(). If timestamps already exist for the media
segments, then the value will be set to segments; if they don't, then the
value will be set to sequence.
If you try to set the mode property value to segments when
the initial value is sequence, an exception will be thrown. The existing
segment order must be maintained in sequence mode. You can, however, change
the value from segments to sequence. It just means the play
order will be fixed, and new timestamps generated to reflect this.
This property cannot be changed during while the SourceBuffer is
processing either an {{domxref("SourceBuffer.appendBuffer","appendBuffer()")}} or
{{domxref("SourceBuffer.remove","remove()")}} call.
A string.
The following exceptions may be thrown when setting a new value for this property:
InvalidAccessError {{domxref("DOMException")}}
segments when the
initial value is sequence.InvalidStateError {{domxref("DOMException")}}
true), the last media segment appended to this
SourceBuffer is incomplete, or this
SourceBuffer has been removed from the
{{domxref("MediaSource")}}.This snippet sets the sourceBuffer mode to 'sequence' if it
is currently set to 'segments', thus setting the play order to the sequence
in which media segments are appended.
const curMode = sourceBuffer.mode;
if (curMode === "segments") {
sourceBuffer.mode = "sequence";
}
{{Specifications}}
{{Compat}}