Concat workflow operation handler

FFMPEG 1.1 is required for the encoding profile related to this operation!

Overview

The "concat" operation handler has been created to concatenate multiple video tracks into one video track. The concatenation process uses the ffmpeg scale filter which is always re-encoding the videos, this means the resulting video has most likely a loss of quality.

The internal ffmpeg command is using the following filters: scale, pad and setdar for scaling all videos to a similar size including letterboxing, aevalsrc for creating silent audio streams and of course the concat for the actual concatenation step. More info can be found here: https://trac.ffmpeg.org/wiki/FilteringGuide

Sample complex concat filter command

-filter_complex "[0:v]scale=iw*min(640/iw\,480/ih):ih*min(640/iw\,480/ih),pad=640:480:(ow-iw)/2:(oh-ih)/2,setdar=4:3[b];[1:v]scale=iw*min(640/iw\,480/ih):ih*min(640/iw\,480/ih),pad=640:480:(ow-iw)/2:(oh-ih)/2,setdar=4:3[c];[2:v]scale=iw*min(640/iw\,480/ih):ih*min(640/iw\,480/ih),pad=640:480:(ow-iw)/2:(oh-ih)/2,setdar=4:3[d];aevalsrc=0::d=1[silent];[b][0:a][c][silent][d][2:a]concat=n=3:v=1:a=1[v][a]" -map '[v]' -map '[a]'

Usage

This operation is quite similar to the compose operation. The only difference is that the input properties are not only limited to one "source-flavor" and "source-tag". The operation supports multiple flavor and tags as input. To add multiple source, add different key with the prefix "source-flavor-"/"source-tag-" and an incremental number starting with 0. For example:

• source-flavor-0
• source-flavor-1
• source-flavor-..

Configuration keys

Key	Required	Description	Default Value	Example
source-flavor-part-X	false	An iterative list of part/flavor to use as input track.	NULL
presenter/trimmed	source-tag-part-X	false	An iterative list of part/tag to use as input track.	NULL
source-to-concate	source-flavor-part-X-mandatory	false	Define the flavor part-X as an optional track for concatenation.	false
source-tag-part-X-mandatory	false	Define the tag part-X as an optional track for concatenation.	false	true
encoding-profile	true	Define the encoding-profile to use for the concatenation operation. See example of profile below.	NULL	concat
target-flavor	true	Define the flavor(s) to add to the output track.	NULL	presenter/concat
target-tags	false	Define the tag(s) to add to the output track	NULL	engage-download
output-resolution	true	Define the output resolution in width, height or take it from one of the given parts	NULL	1900x1080, part-1

Example

Example of an concat operation in a workflow definition.

<!-- Add intro and outro part to the presenter track -->
<operation
  id="concat"
  fail-on-error="true"
  exception-handler-workflow="error"
  description="Concatenate the presenter track and the intro/outro videos.">
  <configurations>
    <configuration key="source-flavor-part-0">intro/source</configuration>
    <configuration key="source-flavor-part-1">presenter/trimmed</configuration>
    <configuration key="source-flavor-part-1-mandatory">true</configuration>
    <configuration key="source-flavor-part-2">outro/source</configuration>
    <configuration key="target-flavor">presenter/concat</configuration>
    <configuration key="target-tags">engage-download,engage-streaming</configuration>
    <configuration key="encoding-profile">concat</configuration>
    <configuration key="output-resolution">1920x1080</configuration>
  </configurations>
</operation>

Encoding profile

The encoding profile command must contain the the #{concatCommand} parameter.

# Concat
profile.concat.name = concat
profile.concat.input = visual
profile.concat.output = visual
profile.concat.suffix = -concatenated.mp4
profile.concat.mimetype = video/mp4
profile.concat.ffmpeg.command = #{concatCommand} -acodec libfaac -b:a 128k -vcodec mpeg4 -b:v 1200k
-flags +aic+mv4 #{out.dir}/#{out.name}#{out.suffix}