The EMS is packaged with a software encoder which provides a wide variety of additional functionality to the EMS. EvoStream has chosen LibAV’s AVConv encoder to be distributed, unmodified, along with the EMS. Source code for AVConv can be found at http://libav.org/download.html. EvoStream complies fully with the GPL in relation to the distribution of AVConv.
The EMS can be easily configured to use ANY software encoder. If a different software encoder is desired, the integration requires only a change to a script, something that can be done on-demand.
Transcoding is an inherently complicated process, given the huge variety of options available for compressing audio and video. The EMS provides a simple transcode API which makes the entire process very easy.
Note:
Transcoding requires SIGNIFICANT computing resources and will severely impact performance. A general conservative guideline is that to accomplish one transcoding job per CPU core for HD streams.
How To
Changing Stream Bitrates
A common use case for transcoding involves the “translating”(down-scaling) of an HD stream into lower bitrates to support Adaptive Streaming protocols and smaller clients like Android and iOS devices.
The simplest way to accomplish this is to bring the original HD stream into the EMS. You can then issue a command similar to the following to create multiple streams with lower bitrates:
Format:
transcode source=rtmp://<stream_source> groupName=<groupName> videoBitrates=<bitrate> destinations=<destinationName>
Sample API Call:
transcode source=rtmp://s2pchzxmtymn2k.cloudfront.net/cfx/st/mp4:sintel.mp4 groupName=group1 videoBitrates=100k,200k,300k destinations=stream100,stream200,stream300
JSON Response:
Command entered successfully!
Transcoding successfully started.
audioBitrates:
-- na
-- na
-- na
croppings:
-- na
-- na
-- na
destinations:
-- stream100
-- stream200
-- stream300
dstUriPrefix: -f flv tcp://localhost:6666/
emsTargetStreamName: stream300
fullBinaryPath: C:\EvoStream_171\emsTranscoder.bat
groupName: group1
keepAlive: true
localStreamName:
source: rtmp://s2pchzxmtymn2k.cloudfront.net/cfx/st/mp4:sintel.mp4
srcUriPrefix: rtsp://localhost:5544/
targetStreamNames:
-- stream100
-- stream200
-- stream300
videoBitrates:
-- 100k
-- 200k
-- 300k
videoSizes:
-- na
-- na
-- na
This command takes the Source1 stream and creates 3 new streams within the EMS. stream100 has a bit rate of 100kbps, stream200 has a bit rate of 200kbps and stream300 has a bit rate of 300kbps. You can check the created streams by sending listStreams.
You can then take each of those final streams and access them directly (IE: via RTMP or RTSP), or you can create an HLS group out of them to create an adaptive bitrate stream for iOS devices:
Creating HLS from Transcoded Stream:
createhlsstream localstreamnames=stream100,stream200,stream300 targetfolder=/mywebroot/hls groupname=MyGroup playlisttype=rolling playlistLength=10 chunkLength=20
Using Different Codecs
The EMS requires streams to be of type H.264/AAC, but that may not be the format your stream source is in. The EMS Transcoder can be used to convert your source stream into H.264/AAC:
Format:
transcode source=<stream_source>/localStreamName groupName=<groupName> videoBitrates=<bitrate> audioBitrates=<bitrate> destinations=<destinationName>
Sample API Call:
transcode source=rtsp://IpOfStreamSource:554/myStream groupName=group1 videoBitrates=5000k audioBitrates=800k destinations=myTranscodedStream
JSON Response:
Command entered successfully!
Transcoding successfully started.
audioBitrates:
-- 800k
croppings:
-- na
destinations:
-- myTranscodedStream
dstUriPrefix: -f flv tcp://localhost:6666/
emsTargetStreamName: myTranscodedStream
fullBinaryPath: C:\EvoStream_171\emsTranscoder.bat
groupName: group1
keepAlive: true
localStreamName:
source: rtsp://127.0.0.1:5544/myStream
srcUriPrefix: rtsp://localhost:5544/
targetStreamNames:
-- myTranscodedStream
videoBitrates:
-- 5000k
videoSizes:
-- na
This command pulls the source stream from its RTSP source directly, transcodes it, and passes it to the EMS as the destinationName. The videoBitrates parameter must be specified when transcoding the video codec. The audioBitrates parameter must be specified when transcoding the audio codec. If either the audio or video does not need to be transcoded, that parameter may be skipped. Here it is assumed that the source stream has a video bit rate of around 5Mbps and audio bitrate of around 800kbps.
Use files as input and/or output:
This will change your input stream to an output file, or an input file to an output file.
Format:
transcode source=file://path_to_sourceFile groupName=group videoBitrates=<bitrate> audioBitrates=<bitrate> destinations=file://path_to_outputFile
Sample API Call:
transcode source=file://C:\EvoStream\media\bunny.mp4 groupName=group1 videoBitrates=100k audioBitrates=copy destinations=file://C:\EvoStream\media\transcoded.mp4 keepAlive=0
JSON Response:
Command entered successfully!
Transcoding successfully started.
audioBitrates:
-- copy
croppings:
-- na
destinations:
-- file://C:\EvoStream\media\transcoded.mp4
dstUriPrefix: -f flv tcp://localhost:6666/
emsTargetStreamName:
fullBinaryPath: C:\EvoStream\emsTranscoder.bat
groupName: group1
keepAlive: false
localStreamName:
source: file://C:\EvoStream\media\bunny.mp4
srcUriPrefix: rtsp://localhost:5544/
targetStreamNames:
-- na
videoBitrates:
-- 100k
videoSizes:
-- na
Video Overlays - Watermarking
The EMS Transcoder may be used to generate overlays on top of your videos. PNG or JPEG images with alpha layers (transparency) should be used. The image must be at the same or smaller resolution (height and width) of the video you are overlaying. The overlay file will be placed at the top-left corner of the video. To create the overlay, simply issue the following command:
Format:
transcode source=<localStreamName> groupName=<groupName> overlays0=<path/to/image.ext> destinations=destinationName
Sample API Call:
transcode source=myStream groupName=group1 overlays=/path/to/evologo.jpg destinations=OverlayedStream
JSON Response:
Command entered successfully!
Transcoding successfully started.
audioBitrates:
-- na
croppings:
-- na
destinations:
-- OverlayedStream
dstUriPrefix: -f flv tcp://localhost:6666/
emsTargetStreamName: OverlayedStream
fullBinaryPath: C:\EvoStream_171\emsTranscoder.bat
groupName: group1
keepAlive: true
localStreamName: myStream
source: stream100
srcUriPrefix: rtsp://localhost:5544/
targetStreamNames:
-- OverlayedStream
videoBitrates:
-- na
videoSizes:
-- na
Cropping
In some cases, you may want to crop a video and focus on just a portion of the video. The EMS Transcoder supports video cropping.
Format:
transcode source=<localStreamName> groupName=<groupName> croppings=<horizontalPosition:verticalPosition:width:height> destinations=destinationName
Sample API:
transcode source=myStream groupName=group1 croppings=0:0:50:50 destinations=CroppedStream
JSON Response:
Command entered successfully!
Transcoding successfully started.
audioBitrates:
-- na
croppings:
-- 0:0:50:50
destinations:
-- CroppedStream
dstUriPrefix: -f flv tcp://localhost:6666/
emsTargetStreamName: CroppedStream
fullBinaryPath: C:\EvoStream_171\emsTranscoder.bat
groupName: group1
keepAlive: true
localStreamName: myStream
source: myStream
srcUriPrefix: rtsp://localhost:5544/
targetStreamNames:
-- CroppedStream
videoBitrates:
-- na
videoSizes:
-- na
This creates a resultant stream containing only a square 50px by 50px from the top right corner of the video. The format for the croppings parameter horizontalPosition:verticalPosition:width:height where horizontalPosition=0 at leftmost pixel, verticalPosition=0 at uppermost pixel.
Force TCP for inbound RTSP
transcode source=rtmp://<RTMP server>/live/streamname groupName=group videoBitrates=copy videoSizes=360x200 $EMS_RTSP_TRANSPORT=tcp
Stopping Transcoding Process(es)
You need to Issue a removeconfig API to stop the transcoding.
Format:
removeConfig groupName=<groupName>
Sample API Call:
removeConfig groupName=group1
JSON Response:
Command entered successfully!
Configuration terminated
All transcoding processes under group1 will be removed.
Enable Transcode Logs
The transcode command calls the emsTranscoder.sh. The logs will help you determine the root cause of the transcode issue. You can enable the transcode logs by doing the following:
-
Enable
transcodelogs by removing the commentin Windows: emsTranscoder.bat
rem echo %TRANSCODER_BIN% %TRANSCODE% //remove remin Linux: emsTranscoder.sh
#echo "$TRANSCODER_BIN $TRANSCODE" //remove # -
Run EMS Console, do the
transcodecommand, it will also print to the screen the evo-avconv command that it is executing -
Copy the evo-avconv result
Sample log:
evo-avconv -y -i rtmp://s2pchzxmtymn2k.cloudfront.net/cfx/st/mp4:sintel.mp4 -b:v 100K -c:v libx264 -c:a copy -metadata streamName=testTransDest rtmp://192.168.2.35/live/testTransDest -
Paste the evo-avconv result in new console (locate in evo-avconv executable)
Sample log:
C:\EvoStream>evo-avconv -y -i rtmp://s2pchzxmtymn2k.cloudfront.net/cfx/st/mp4:sintel.mp4 -b:v 10 0K -c:v libx264 -c:a copy -metadata streamName=testTransDest rtmp://192.168.2.35/live/testTransDest avconv version 11.3, Copyright (c) 2000-2014 the Libav developers built on Jul 15 2015 10:16:52 with gcc 4.8 (GCC) [flv @ 0000000000302da0] max_analyze_duration 5000000 reached Input #0, flv, from 'rtmp://s2pchzxmtymn2k.cloudfront.net/cfx/st/mp4:sintel.mp4': Metadata: moovPosition : 40 avcprofile : 66 avclevel : 30 aacaot : 2 videoframerate : 24 audiochannels : 2 ©too : Lavf52.84.0 length : 2293760 timescale : 44100 sampletype : mp4a Duration: 00:00:52.20, start: 0.000000, bitrate: N/A Stream #0.0: Video: h264 (Constrained Baseline), yuv420p, 720x306 [PAR 254:255 DAR 2032:867], 24 fps, 1k tbn, 48 tbc Stream #0.1: Audio: aac, 44100 Hz, stereo, fltp Unable to find a suitable output format for 'rtmp://192.168.2.35/live/testTransDest'