/// <summary>
/// Processes the media subtitles and finds and handles external subtitle files
/// </summary>
/// <param name="config">The <see cref="DashConfig"/></param>
/// <param name="subtitleFiles">The subtitle stream files</param>
/// <param name="startFileIndex">The index additional subtitles need to start at. This should be the max index of the ffmpeg pieces +1</param>
protected virtual IEnumerable <SubtitleStreamCommand> ProcessSubtitles(DashConfig config, IEnumerable <SubtitleStreamCommand> subtitleFiles, int startFileIndex)
{
// Move subtitles found in media
foreach (var subFile in subtitleFiles)
{
string oldPath = subFile.Path;
subFile.Path = Path.Combine(config.OutputDirectory, Path.GetFileName(subFile.Path));
yield return(subFile);
if (oldPath != subFile.Path)
{
if (File.Exists(subFile.Path))
{
File.Delete(subFile.Path);
}
File.Move(oldPath, subFile.Path);
}
}
// Add external subtitles
string baseFilename = Path.GetFileNameWithoutExtension(config.InputFilePath);
foreach (var vttFile in Directory.EnumerateFiles(Path.GetDirectoryName(config.InputFilePath), baseFilename + "*", SearchOption.TopDirectoryOnly))
{
if (vttFile.EndsWith(".vtt"))
{
string vttFilename = Path.GetFileName(vttFile);
string vttName = GetSubtitleName(vttFilename);
string vttOutputPath = Path.Combine(config.OutputDirectory, $"{config.OutputFileName}_subtitle_{vttName}_{startFileIndex}.vtt");
var subFile = new SubtitleStreamCommand()
{
Index = startFileIndex,
Path = vttOutputPath,
Language = $"{vttName}_{startFileIndex}"
};
startFileIndex++;
File.Copy(vttFile, vttOutputPath, true);
yield return(subFile);
}
}
}
/// <summary>
/// Generates and appends commands for the given subtitle streams to the internal command set.
/// </summary>
public virtual FFmpegCommandBuilder WithSubtitleCommands(IEnumerable <MediaStream> streams)
{
if (!streams.Any())
{
return(this);
}
foreach (MediaStream subtitleStream in streams)
{
if (!Constants.SupportedSubtitleCodecs.Contains(subtitleStream.codec_name))
{
continue;
}
string language = subtitleStream.tag
.Where(x => x.key == "language")
.Select(x => x.value)
.FirstOrDefault();
if (language is null)
{
language = "und";
}
string path = Path.Combine(OutputDirectory, $"{OutputBaseFilename}_subtitle_{language}_{subtitleStream.index}.vtt");
SubtitleStreamCommand command = new SubtitleStreamCommand()
{
Index = subtitleStream.index,
Language = language,
Path = path,
Argument = string.Join(" ", new string[]
{
$"-map 0:{subtitleStream.index}",
'"' + path + '"'
})
};
subtitleFiles.Add(command);
}
return(this);
}
/// <summary>
/// Generates an MPD AdaptationSet representing a subtitle stream.
/// </summary>
/// <param name="representationId">A generated unique representation ID to use for this AdaptationSet's </param>
/// <param name="subtitle">The subtitle stream, representing a VTT file on disk.</param>
/// <param name="nextRepresentationId">Must be set to the next unused representation ID.</param>
/// <returns>An adaptation set to add to the output MPD file. May be null to not add this subtitle.</returns>
protected virtual AdaptationSet GenerateSubtitleAdaptationSet(int representationId, SubtitleStreamCommand subtitle, out int nextRepresentationId)
{
nextRepresentationId = representationId + 1;
return(new AdaptationSet()
{
MimeType = "text/vtt",
Lang = subtitle.Language,
ContentType = "text",
Representation = new List <Representation>()
{
new Representation()
{
Id = representationId.ToString(),
Bandwidth = 256,
BaseURL = new List <string>()
{
Path.GetFileName(subtitle.Path)
}
}
},
Role = new DescriptorType()
{
SchemeIdUri = "urn:gpac:dash:role:2013",
Value = $"{subtitle.Language} {representationId}"
}
});
}
