Thumbnail generation - First frame which is not 'black'

Julia Kornich on Tue, 02 Dec 2014 03:45:56

You can achieve that if you modify an encoder preset by including the thumbnail generation info. 

  <MediaFile
    ThumbnailMode="BestFrame"
    ThumbnailJpegCompression="75"
    ThumbnailCodec="Jpeg"
    ThumbnailSize="100%, 100%"
    ThumbnailEmbed="False">

By the end of the encoding job, the thumbnail will be in the output asset along with other output files. 

For example, I uploaded a wmv file that had black frames at the beginning.

I modified the "H264 Adaptive Bitrate MP4 Set 720p.xml" preset (located here) to include the thumbnail generation info. 

<?xml version="1.0" encoding="utf-16"?>
<!--Created for Azure Media Encoder, July 30 2014 -->
<Presets>
 <Preset
   Version="5.0">
   <Job />
   <MediaFile
     DeinterlaceMode="AutoPixelAdaptive"
     ResizeQuality="Super"
     AudioGainLevel="1"
     VideoResizeMode="Stretch"
     ThumbnailTime="00:00:00"
     ThumbnailMode="BestFrame"
     ThumbnailJpegCompression="75"
     ThumbnailCodec="Jpeg"
     ThumbnailSize="100%, 100%"
     ThumbnailEmbed="False">
. . . 

I used the following SDK code to encode an asset that contains WMV to H264 Adaptive Bitrate MP4 Set 720p and also generate a thumbnail jpg file.

static public IAsset EncodeToAdaptiveBitrateMP4Set(IAsset inputAsset)
{
    var encodingPreset = "H264 Adaptive Bitrate MP4 Set 720p";

    IJob job = _context.Jobs.Create(String.Format("Encoding WMV {0} to {1}",
                            inputAsset.Name,
                            encodingPreset));

    var mediaProcessors =
        _context.MediaProcessors.Where(p => p.Name.Contains("Media Encoder")).ToList();

    var latestMediaProcessor =
        mediaProcessors.OrderBy(mp => new Version(mp.Version)).LastOrDefault();

    string configuration = File.ReadAllText("H264 Adaptive Bitrate MP4 Set 720p with Thumbnail.xml");

    ITask encodeTask = job.Tasks.AddNew("Encoding", latestMediaProcessor, configuration, TaskOptions.None);
    encodeTask.InputAssets.Add(inputAsset);
    encodeTask.OutputAssets.AddNew(String.Format("{0} as {1}", inputAsset.Name, encodingPreset), AssetCreationOptions.None);

    job.StateChanged += new EventHandler<JobStateChangedEventArgs>(JobStateChanged);
    job.Submit();
    job.GetExecutionProgressTask(CancellationToken.None).Wait();

    return job.OutputMediaAssets[0];
}

This posting is provided "AS IS" with no warranties, and confers no rights.

Andrei NS on Fri, 05 Dec 2014 16:21:05

Thanks for your response, I have few more questions:

1. I haven't been able to find any documentation about the MediaFile node, do you know where I can find it?

2. In the example you gave, what is the filename of the thumbnail? How can I set it?

3. I'm generating the thumbnail with a separate task, based on the information from here: http://msdn.microsoft.com/en-us/library/azure/hh973624.aspx 

If I'm going to set the 'ThumbnailXXX' attributes on MediaNode as you suggested, I suppose I won't need the  thumbnail generation task anymore?

Julia Kornich on Fri, 05 Dec 2014 19:55:57

Andrei,

1. The <MediaFile> element is part of the Media Encoder presets defined here.

2. The name contains the input file name plus some encoding information appended by _Thumb.jpg. In my case the name of the file is BigBuckBunny_H264_3400kbps_AAC_und_ch2_96kbps_Thumb.jpg.

3. The creation of a thumbnail based on the first  non-black frame is not currently supported by the Thumbnail preset. Using an encoding job to generate the thumbnail based on the BestFrame is a workaround. 

thank you,

Julia