Ejemplo n.º 1
0
        /// <summary>
        /// Opens MP3 from a stream rather than a file
        /// Will not dispose of this stream itself
        /// </summary>
        /// <param name="inputStream">The incoming stream containing MP3 data</param>
        /// <param name="frameDecompressorBuilder">Factory method to build a frame decompressor</param>
        public Mp3FileReader(Stream inputStream, FrameDecompressorBuilder frameDecompressorBuilder)
        {
            if (inputStream == null) throw new ArgumentNullException("inputStream");
            try
            {
                mp3Stream = inputStream;
                id3v2Tag = Id3v2Tag.ReadTag(mp3Stream);

                dataStartPosition = mp3Stream.Position;
                var firstFrame = Mp3Frame.LoadFromStream(mp3Stream);
                if (firstFrame == null)
                    throw new InvalidDataException("Invalid MP3 file - no MP3 Frames Detected");
                double bitRate = firstFrame.BitRate;
                xingHeader = XingHeader.LoadXingHeader(firstFrame);
                // If the header exists, we can skip over it when decoding the rest of the file
                if (xingHeader != null) dataStartPosition = mp3Stream.Position;

                // workaround for a longstanding issue with some files failing to load
                // because they report a spurious sample rate change
                var secondFrame = Mp3Frame.LoadFromStream(mp3Stream);
                if (secondFrame != null &&
                    (secondFrame.SampleRate != firstFrame.SampleRate ||
                     secondFrame.ChannelMode != firstFrame.ChannelMode))
                {
                    // assume that the first frame was some kind of VBR/LAME header that we failed to recognise properly
                    dataStartPosition = secondFrame.FileOffset;
                    // forget about the first frame, the second one is the first one we really care about
                    firstFrame = secondFrame;
                }

                this.mp3DataLength = mp3Stream.Length - dataStartPosition;

                // try for an ID3v1 tag as well
                mp3Stream.Position = mp3Stream.Length - 128;
                byte[] tag = new byte[128];
                mp3Stream.Read(tag, 0, 128);
                if (tag[0] == 'T' && tag[1] == 'A' && tag[2] == 'G')
                {
                    id3v1Tag = tag;
                    this.mp3DataLength -= 128;
                }

                mp3Stream.Position = dataStartPosition;

                // create a temporary MP3 format before we know the real bitrate
                this.Mp3WaveFormat = new Mp3WaveFormat(firstFrame.SampleRate,
                    firstFrame.ChannelMode == ChannelMode.Mono ? 1 : 2, firstFrame.FrameLength, (int) bitRate);

                CreateTableOfContents();
                this.tocIndex = 0;

                // [Bit rate in Kilobits/sec] = [Length in kbits] / [time in seconds] 
                //                            = [Length in bits ] / [time in milliseconds]

                // Note: in audio, 1 kilobit = 1000 bits.
                // Calculated as a double to minimize rounding errors
                bitRate = (mp3DataLength*8.0/TotalSeconds());

                mp3Stream.Position = dataStartPosition;

                // now we know the real bitrate we can create an accurate MP3 WaveFormat
                this.Mp3WaveFormat = new Mp3WaveFormat(firstFrame.SampleRate,
                    firstFrame.ChannelMode == ChannelMode.Mono ? 1 : 2, firstFrame.FrameLength, (int) bitRate);
                decompressor = frameDecompressorBuilder(Mp3WaveFormat);
                this.waveFormat = decompressor.OutputFormat;
                this.bytesPerSample = (decompressor.OutputFormat.BitsPerSample)/8*decompressor.OutputFormat.Channels;
                // no MP3 frames have more than 1152 samples in them
                // some MP3s I seem to get double
                this.decompressBuffer = new byte[1152*bytesPerSample*2];
            }
            catch (Exception)
            {
                if (ownInputStream) inputStream.Dispose();
                throw;
            }
        }
Ejemplo n.º 2
0
        /// <summary>
        /// Opens MP3 from a stream rather than a file
        /// Will not dispose of this stream itself
        /// </summary>
        /// <param name="inputStream">The incoming stream containing MP3 data</param>
        /// <param name="frameDecompressorBuilder">Factory method to build a frame decompressor</param>
        public Mp3FileReader(Stream inputStream, FrameDecompressorBuilder frameDecompressorBuilder)
        {
            if (inputStream == null)
            {
                throw new ArgumentNullException("inputStream");
            }
            try
            {
                mp3Stream = inputStream;
                id3v2Tag  = Id3v2Tag.ReadTag(mp3Stream);

                dataStartPosition = mp3Stream.Position;
                var firstFrame = Mp3Frame.LoadFromStream(mp3Stream);
                if (firstFrame == null)
                {
                    throw new InvalidDataException("Invalid MP3 file - no MP3 Frames Detected");
                }
                double bitRate = firstFrame.BitRate;
                xingHeader = XingHeader.LoadXingHeader(firstFrame);
                // If the header exists, we can skip over it when decoding the rest of the file
                if (xingHeader != null)
                {
                    dataStartPosition = mp3Stream.Position;
                }

                // workaround for a longstanding issue with some files failing to load
                // because they report a spurious sample rate change
                var secondFrame = Mp3Frame.LoadFromStream(mp3Stream);
                if (secondFrame != null &&
                    (secondFrame.SampleRate != firstFrame.SampleRate ||
                     secondFrame.ChannelMode != firstFrame.ChannelMode))
                {
                    // assume that the first frame was some kind of VBR/LAME header that we failed to recognise properly
                    dataStartPosition = secondFrame.FileOffset;
                    // forget about the first frame, the second one is the first one we really care about
                    firstFrame = secondFrame;
                }

                this.mp3DataLength = mp3Stream.Length - dataStartPosition;

                // try for an ID3v1 tag as well
                mp3Stream.Position = mp3Stream.Length - 128;
                byte[] tag = new byte[128];
                mp3Stream.Read(tag, 0, 128);
                if (tag[0] == 'T' && tag[1] == 'A' && tag[2] == 'G')
                {
                    id3v1Tag            = tag;
                    this.mp3DataLength -= 128;
                }

                mp3Stream.Position = dataStartPosition;

                // create a temporary MP3 format before we know the real bitrate
                this.Mp3WaveFormat = new Mp3WaveFormat(firstFrame.SampleRate,
                                                       firstFrame.ChannelMode == ChannelMode.Mono ? 1 : 2, firstFrame.FrameLength, (int)bitRate);

                CreateTableOfContents();
                this.tocIndex = 0;

                // [Bit rate in Kilobits/sec] = [Length in kbits] / [time in seconds]
                //                            = [Length in bits ] / [time in milliseconds]

                // Note: in audio, 1 kilobit = 1000 bits.
                // Calculated as a double to minimize rounding errors
                bitRate = (mp3DataLength * 8.0 / TotalSeconds());

                mp3Stream.Position = dataStartPosition;

                // now we know the real bitrate we can create an accurate MP3 WaveFormat
                this.Mp3WaveFormat = new Mp3WaveFormat(firstFrame.SampleRate,
                                                       firstFrame.ChannelMode == ChannelMode.Mono ? 1 : 2, firstFrame.FrameLength, (int)bitRate);
                decompressor        = frameDecompressorBuilder(Mp3WaveFormat);
                this.waveFormat     = decompressor.OutputFormat;
                this.bytesPerSample = (decompressor.OutputFormat.BitsPerSample) / 8 * decompressor.OutputFormat.Channels;
                // no MP3 frames have more than 1152 samples in them
                // some MP3s I seem to get double
                this.decompressBuffer = new byte[1152 * bytesPerSample * 2];
            }
            catch (Exception)
            {
                if (ownInputStream)
                {
                    inputStream.Dispose();
                }
                throw;
            }
        }