private static void ValidateAt9File(RiffParser parser)
{
if (parser.RiffChunk.Type != "WAVE")
{
throw new InvalidDataException("Not a valid WAVE file");
}
WaveFmtChunk fmt = parser.GetSubChunk <WaveFmtChunk>("fmt ") ?? throw new InvalidDataException("File must have a valid fmt chunk");
At9WaveExtensible ext = fmt.Ext as At9WaveExtensible ?? throw new InvalidDataException("File must have a format chunk extension");
if (parser.GetSubChunk <At9FactChunk>("fact") == null)
{
throw new InvalidDataException("File must have a valid fact chunk");
}
if (parser.GetSubChunk <At9DataChunk>("data") == null)
{
throw new InvalidDataException("File must have a valid data chunk");
}
if (fmt.ChannelCount == 0)
{
throw new InvalidDataException("Channel count must not be zero");
}
if (ext.SubFormat != MediaSubtypes.MediaSubtypeAtrac9)
{
throw new InvalidDataException($"Must contain ATRAC9 data. Has unsupported SubFormat {ext.SubFormat}");
}
}
public At9DataChunk(RiffParser parser, BinaryReader reader) : base(reader)
{
// Do not trust the BlockAlign field in the fmt chunk to equal the superframe size.
// Some AT9 files have an invalid number in there.
// Calculate the size using the ATRAC9 DataConfig instead.
At9WaveExtensible ext = parser.GetSubChunk <WaveFmtChunk>("fmt ")?.Ext as At9WaveExtensible ??
throw new InvalidDataException("fmt chunk must come before data chunk");
At9FactChunk fact = parser.GetSubChunk <At9FactChunk>("fact") ??
throw new InvalidDataException("fact chunk must come before data chunk");
var config = new Atrac9Config(ext.ConfigData);
FrameCount = (fact.SampleCount + fact.EncoderDelaySamples).DivideByRoundUp(config.SuperframeSamples);
int dataSize = FrameCount * config.SuperframeBytes;
if (dataSize > reader.BaseStream.Length - reader.BaseStream.Position)
{
throw new InvalidDataException("Required AT9 length is greater than the number of bytes remaining in the file.");
}
AudioData = reader.BaseStream.DeInterleave(dataSize, config.SuperframeBytes, FrameCount);
}