transcode

This function changes the compression characteristics of an audio and/or video stream. This function allows you to change the resolution of a source stream, change the bitrate of a stream, change a VP8 or MPEG2 stream into H.264 and much more. This function will also allow users to create overlays on the final stream as well as crop streams.

Transcoding requires SIGNIFICANT computing resources and will severely impact performance. A general guideline is that you can accomplish one transcoding job per CPU core for HD streams.

IMPORTANT NOTES:

1. For any parameter that is pluralized, you may specify one value, or multiple. Multiple values must be separated by only a comma (comma-delimited). Specifying multiple values indicates multiple new streams will be created.
2. There must be the same number of values for all pluralized parameters. Order is important: all first values are grouped together to make the first stream, all second parameters are grouped to make the second stream, etc…
3. Video related parameters are ignored if the parameter videoBitrates is not specified.
4. Audio related parameters are ignored if the parameter audioBitrates is not specified.

This function has the following parameters:

An example of the transcode command is:

transcode source=rtmp://<RTMP server>/live/streamname groupName=group videoBitrates=200k destinations=stream1

Transcode Examples

To transcode an RTMP source into different video bitratesand send back to EMS

transcode source=rtmp://<RTMP server>/live/streamname groupName=group videoBitrates=100k,200k,300k destinations=stream100,stream200,stream300

To transcode an existing EMS stream into a different audio channel count and send to an RTMP server

transcode source=stream1 groupName=group audioBitrates=copy audioChannelsCounts=1 destinations=rtmp://<RTMP server 2> targetStreamNames=streamMono

To use files as input and/or output

transcode source=file://C:\videos\test.mp4 groupName=group videoBitrates=100k audioBitrates=copy destinations=file://C:\videos\out.mp4

To force TCP for inbound RTSP

transcode source=rtsp://<RTSP server>/live/streamname groupName=group videoBitrates=copy videoSizes=360x200 $EMS_RTSP_TRANSPORT=tcp

To use command flags

transcode source=rtmp://<RTSP server>/live/streamname groupName=group destinations=destinationStream commandFlags="<command>"

To stop a running transcoding process(es)

removeConfig groupName=group

Transcoding Customizations:

To configure the transcoder script settings, edit the file config.lua and edit the following entries as needed:

transcoder = {
	scriptPath="emsTranscoder",
	srcUriPrefix="rtsp://localhost:5544/",
	dstUriPrefix="-f flv tcp://localhost:6666/"
},

To change the location of the actual trancoder binary, edit the file emsTranscoder.sh (linux/unix) and emsTranscoder.cmd (windows); and change the following line:

TRANSCODER\_BIN=/usr/bin/evo-avconv (linux/unix)

set TRANSCODER\_BIN= ..\\evo-avconv.exe (windows)

Example:

API Call:

transcode source=rtmp://s2pchzxmtymn2k.cloudfront.net/cfx/st/mp4:sintel.mp4 groupName=group videoBitrates=200k destinations=stream1

JSON Response:

{
"data":{
    "audioAdvancedParamsProfiles":["na"],
    "audioBitrates":["na"],
    "audioChannelsCounts":["na"],
    "audioFrequencies":["na"],
    "croppings":["na"],
    "destinations":["stream1"],
    "dstUriPrefix":"-f flv tcp:\/\/localhost:6666\/",
    "emsTargetStreamName":"stream1",
    "fullBinaryPath":"C:\\EvoStream\\emsTranscoder.bat",
    "groupName":"group",
    "keepAlive":true,
    "localStreamName":"",
    "overlays":["na"],
    "source":"rtmp:\/\/s2pchzxmtymn2k.cloudfront.net\/cfx\/st\/mp4:sintel.mp4",
    "srcUriPrefix":"rtsp:\/\/localhost:5544\/",
    "targetStreamNames":["stream1"],
    "videoAdvancedParamsProfiles":["na"],
    "videoBitrates":["200k"],
    "videoSizes":["na"]
},
"description":"Transcoding successfully started.",
"status":"SUCCESS"
}

The JSON response contains the following details:

• data – The data to parse
  • audioAdvancedParamsProfiles - An array of strings specifying the name of profile presets to be used for audio
  • audioBitrates - An array of integers for target audio output bitrates
  • audioChannelsCounts - An array of values for the target number of audio channels
  • croppings - An array of values for the target cropping positions and size
  • destinations - An array of target URIs or stream names
  • dstUriPrefix - Default destination if destination is a stream name
  • emsTargetStreamName - Target stream name used internally by EMS
  • fullBinaryPath - Actual location of the transcoder binary
  • groupName - Name of the group associated with this transcoding process
  • keepAlive - Transcoding will restart if previously activated
  • localStreamName - Actual EMS stream name of source (if given)
  • overlays - An array of locations for the images to be used as overlays
  • source - The actual stream/file to be used as input for transcoding
  • srcUriPrefix - Default source if given source is a stream name
  • targetStreamNames - An array of the target stream names to be used at the destination
  • videoAdvancedParamsProfiles - An array of strings specifying the name of profile presets to be used for video
  • videoBitrates - An array of values for target video output bitrates
  • videoSizes - An array of values for target video sizes
• description – Describes the result of parsing/executing the command
• status – SUCCESS if the command was parsed and executed successfully, FAIL if not