The roCaptionRenderer component provides a mechanism for BrightScript channels to render closed captions in video played back with the roVideoPlayer. Prior to the v 5.2 Roku firmware, captions could only be rendered in roVideoScreen.
Supported Interfaces
Supported Events
Description
Prior to the 5.2 Roku firmware version, closed captions could only be rendered in roVideoScreen. Now channels that use roVideoPlayer embedded in an roScreen or roImageCanvas can also take advantage of Roku's closed captioning support. roCaptionRenderer supports two different modes, which is set using the SetMode() method. Depending on the mode set, and the type of screen being used, the BrightScript channel needs to do different levels of work to render captions. These different workflows are highlighted in the tables below:
Mode 1
roScreen | roImageCanvas |
---|---|
Call SetScreen() | Call SetScreen() |
Call UpdateCaption() |
Mode 2
roScreen | roImageCanvas |
---|---|
All caption rendering is done by the channel's BrightScript code | All caption rendering is done by the channel's BrightScript code |
BrightScript channels do not create roCaptionRenderer instances directly using CreateObject(). Instead, when an roVideoPlayer is created, it contains an roCaptionRenderer. BrightScript channels call ifVideoPlayer.GetCaptionRenderer() to get the caption renderer associated with their video player.
Sample Code
Function Main() as void
mode = 1
fonts = CreateObject("roFontRegistry")
fonts.Register("pkg:/fonts/vSHandprinted.otf")
font = fonts.GetFont("vSHandprinted", 28, 500, false)
screen = CreateObject("roScreen", true)
port = CreateObject("roMessagePort")
screen.Clear(&h00)
screen.SwapBuffers()
screen.SetMessagePort(port)
timer = CreateObject("roTimespan")
screenSize = {}
screenSize.width = screen.GetWidth()
screenSize.height = screen.GetHeight()
player = CreateObject("roVideoPlayer")
player.SetContentList([
{
Stream : { url :"http://ecn.channel9.msdn.com/o9/content/smf/smoothcontent/elephantsdream/Elephants_Dream_1024-h264-st-aac.ism/manifest" }
StreamFormat : "ism"
TrackIDAudio: "audio_eng"
TrackIDSubtitle: "ism/textstream_eng"
}
])
captions = player.GetCaptionRenderer()
if (mode = 1)
captions.SetScreen(screen)
endif
captions.SetMode(mode)
captions.SetMessagePort(port)
captions.ShowSubtitle(true)
player.play()
while true
msg = wait(250, port)
if type(msg) = "roCaptionRendererEvent"
if msg.isCaptionText()
print "isCaptionText"
if msg.GetMessage() <> invalid and msg.GetMessage() <> ""
DrawCaptionString(screen, screenSize, msg.GetMessage(), font)
timer.Mark()
else
if timer.TotalSeconds() > 2
ClearCaptionString(screen)
endif
endif
else if msg.isCaptionUpdateRequest()
print "isCaptionUpdateRequest()"
UpdateCaptions(screen, captions)
endif
endif
end while
End Function
Function UpdateCaptions(screen as object, captions as object) as Void
screen.Clear(&h00)
captions.UpdateCaption()
screen.SwapBuffers()
End Function
Function DrawCaptionString(screen as object, screenSize as object, caption as String, font as object) as Void
screen.Clear(&h00)
textHeight = font.GetOneLineHeight()
textWidth = font.GetOneLineWidth(caption, screenSize.width)
x = (screenSize.width - textWidth) / 2
y = screenSize.height - textHeight
screen.DrawText(caption, x, y, &hd5d522ff, font)
screen.SwapBuffers()
End Function
Function ClearCaptionString(screen as object) as void
screen.Clear(&h00)
screen.SwapBuffers()
End Function