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31 Aug 2016

Azure Media Service Encoding with custom presets

In this post you will learn how to use custom preset for Azure Media Service Encoding. But before that let's look at a case study or issue which I faced.

Introduction

When I uploaded a 55.5 MB mp4 file and encoded with "H264AdaptiveBitrateMP4Set720p" encoder preset, I received following output files:



















Look into green rectangular highlighted video files in the image, this looks good according to input file size. But if you look at red rectangular highlighted video files, these are *improved* files for adaptive streaming, which looks useless if you compare with my example "a dark line on my face in video can't be removed by system automatically...make sense". Here I'm trying to understand Azure Media Services encoding permutations but increasing file size 2-3 times larger than input file is never a acceptable deal.

Why I should pay more for bandwidth and storage on these large files, how I convince my clients?

On this issue I thought to understand this from community so I posted this here, but I'm still not convinced with answer.

Note: What are exact reasons encoder increases the file size, if you come to know please share with me too?

Is there any way I can define not to create such files when scheduling encoding?

Yes, we can use custom preset file and send it with encoding request to Azure Media Service. Let's see how it works in the code:

//// XML Preset
string name = "UploadedVideo-" + Guid.NewGuid().ToString();
IJob job = context.Jobs.Create(name);
IMediaProcessor processor = GetLatestMediaProcessorByName("Media Encoder Standard", context);
string configuration = System.IO.File.ReadAllText(HttpContext.Server.MapPath("~/MediaServicesCustomPreset.xml"));
ITask task = job.Tasks.AddNew(name + "- encoding task", processor, configuration, TaskOptions.None);
task.InputAssets.Add(inputAsset);
task.OutputAssets.AddNew(name + "-Adaptive-Bitrate-MP4", AssetCreationOptions.None);
job.Submit();
IAsset encodedOutputAsset = job.OutputMediaAssets[0];
string smoothStreamingUri = PublishAssetGetURLs(encodedOutputAsset, fileName);
string assetDetails = "MediaServiceFileName:" + encodedOutputAsset.Name + ", MediaServiceContainerUri:" + encodedOutputAsset.Uri + ", AssetId:" + encodedOutputAsset.Id;

Check code in repository here.

Notice blue highlighted code, that's what I added to send custom preset file with encoding request. I will be using xml preset file, you can use json file too. Let's look at the xml file now.

<?xml version="1.0" encoding="utf-16"?>
<Preset xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" Version="1.0" xmlns="http://www.windowsazure.com/media/encoding/Preset/2014/03">
  <Encoding>
    <H264Video>
      <KeyFrameInterval>00:00:02</KeyFrameInterval>
      <H264Layers>
        <H264Layer>
          <Bitrate>1500</Bitrate>
          <Width>960</Width>
          <Height>540</Height>
          <FrameRate>0/1</FrameRate>
          <Profile>Auto</Profile>
          <Level>auto</Level>
          <BFrames>3</BFrames>
          <ReferenceFrames>3</ReferenceFrames>
          <Slices>0</Slices>
          <AdaptiveBFrame>true</AdaptiveBFrame>
          <EntropyMode>Cabac</EntropyMode>
          <BufferWindow>00:00:05</BufferWindow>
          <MaxBitrate>1500</MaxBitrate>
        </H264Layer>
        <H264Layer>
          <Bitrate>1000</Bitrate>
          <Width>640</Width>
          <Height>360</Height>
          <FrameRate>0/1</FrameRate>
          <Profile>Auto</Profile>
          <Level>auto</Level>
          <BFrames>3</BFrames>
          <ReferenceFrames>3</ReferenceFrames>
          <Slices>0</Slices>
          <AdaptiveBFrame>true</AdaptiveBFrame>
          <EntropyMode>Cabac</EntropyMode>
          <BufferWindow>00:00:05</BufferWindow>
          <MaxBitrate>1000</MaxBitrate>
        </H264Layer>
        <H264Layer>
          <Bitrate>650</Bitrate>
          <Width>640</Width>
          <Height>360</Height>
          <FrameRate>0/1</FrameRate>
          <Profile>Auto</Profile>
          <Level>auto</Level>
          <BFrames>3</BFrames>
          <ReferenceFrames>3</ReferenceFrames>
          <Slices>0</Slices>
          <AdaptiveBFrame>true</AdaptiveBFrame>
          <EntropyMode>Cabac</EntropyMode>
          <BufferWindow>00:00:05</BufferWindow>
          <MaxBitrate>650</MaxBitrate>
        </H264Layer>
        <H264Layer>
          <Bitrate>400</Bitrate>
          <Width>320</Width>
          <Height>180</Height>
          <FrameRate>0/1</FrameRate>
          <Profile>Auto</Profile>
          <Level>auto</Level>
          <BFrames>3</BFrames>
          <ReferenceFrames>3</ReferenceFrames>
          <Slices>0</Slices>
          <AdaptiveBFrame>true</AdaptiveBFrame>
          <EntropyMode>Cabac</EntropyMode>
          <BufferWindow>00:00:05</BufferWindow>
          <MaxBitrate>400</MaxBitrate>
        </H264Layer>
      </H264Layers>
      <Chapters />
    </H264Video>
    <AACAudio>
      <Profile>AACLC</Profile>
      <Channels>2</Channels>
      <SamplingRate>48000</SamplingRate>
      <Bitrate>128</Bitrate>
    </AACAudio>
  </Encoding>
  <Outputs>
    <Output FileName="{Basename}_{Width}x{Height}_{VideoBitrate}.mp4">
      <MP4Format />
    </Output>
  </Outputs>
</Preset>

Check code in repository here.

If we do not pass custom preset file to Azure Media Service, then they use their default preset file which has higher bitrates and they don't have better logic to check input file bitrate and based on this decide new bitrates, this is what I understood.

So, I removed higher bitrate encoding from my preset file and this does the work. This has one disadvantage is that, any superb video quality will be loosed because preset is hardcoded for every video file. But, at-least now I have opportunity to write this bitrate dynamically based on video being uploaded through our service. And then send this new bitrate to Azure Media Services. Check the issue log here.

Hope this helps.

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