我以不同的方式使用音频制作了几个项目： midi文件,语音接口, 调用 Windows DLL, 和读/写 WAV 文件.
这次我将再次使用 WAV 文件。 JMP 的 BlobToMatrix 和 MatrixToBlob 函数可对 blob（二进制大对象）进行操作。 LoadTextFile 和 SaveTextFile 知道如何读取和写入 blob。 WAV 文件是一个二进制对象（在文本编辑器中打开 WAV 文件不会有太多乐趣）。 JSL 矩阵中二进制字节的内存表示是八个字节长，这意味着 1GB（1.5 小时 16 位 44.1KHz 立体声）WAV 文件需要 8GB 内存。 对于我需要的 60 秒文件，这不是问题。同样的想法可以用于任何中等大小的二进制文件，而不仅仅是 WAV，但正如您将看到的，解码二进制文件很复杂。
在之前的邮政我从网络日志中收集数据；我正在使用来自的 IP 到位置文件极智将 IP 地址转换为位置和地名。 通过跨时间切片数据（一个月长的日志文件），我可以制作视频。 这是显示一帧的图形生成器。 我将制作 1800（30FPS * 60 秒）。
Color indicates five lat-lon clusters颜色表示五个 lat-lon 集群
JMP 的聚类平台之一使用纬度和经度将点分为五个聚类；每个集群中的活动将驱动音乐的某些方面与视频一起使用。 音乐生成算法使用状态机那是从这个想法. 和弦过渡由其中一个颜色组驱动，打击乐器部分由另一个颜色组驱动，还有吉他和贝斯吉他。 可能我没有使用所有五种颜色；当我有一些听起来不错的东西时，我就停下来了。 随机不是好声音。
乐器声音（合唱、吉他、打击乐）是从我制作的 WAV 文件样本中加载的LMMS . 在几次错误的开始之后，我决定将样本加载到 JMP 中的最简单方法是将一个仪器的一整套音符放在一个文件中，间隔均匀，音符之间有一些死时间。
Really low guitar notes at the start of the WAV fileWAV 文件开头的吉他音符非常低
合唱团相同，打击乐相似。 保存这些文件，然后像这样将它们加载到 JMP 中：
// RIFF loader
RiffUtil = New Namespace(
"RiffUtil"
);
这将是一个大型项目，因此从命名空间开始，以帮助将细节与项目的其他部分隔离开来。 RIFF 原来是 WAV 文件背后的文件格式的名称。 这个名称空间中将有几个实用函数。 接下来，添加一个函数来加载 WAV。
RiffUtil:loadWav = Function( {filename}, {Default Local},
riff = RiffUtil:load( filename );
{fmtOffset, fmtLength} = riff:chunks["fmt "];
riff:offset = fmtOffset;
// http://soundfile.sapp.org/doc/WaveFormat/
//JMP offset is 1-based, these are 0-based
//20 2 AudioFormat PCM = 1 (i.e. Linear quantization)
// Values other than 1 indicate some
// form of compression.
q = RiffUtil:getShort( riff, 1 );
riff:AudioFormat = q[1];
If( riff:AudioFormat != 1, Throw( "not PCM audio" ) );
//22 2 NumChannels Mono = 1, Stereo = 2, etc.
q = RiffUtil:getShort( riff, 1 );
riff:NumChannels = q[1];
If( riff:NumChannels != 2, Throw( "not 2-channel stereo" ) );
//24 4 SampleRate 8000, 44100, etc.
q = RiffUtil:getLong( riff, 1 );
riff:SampleRate = q[1];
If( riff:SampleRate != 44100, Throw( "not 44.1 kHz" ) );
//28 4 ByteRate == SampleRate * NumChannels * BitsPerSample/8
q = RiffUtil:getLong( riff, 1 );
riff:ByteRate = q[1];
If( riff:ByteRate != 44100 * 2 * 2, Throw( "not expected byte rate" ) );
//32 2 BlockAlign == NumChannels * BitsPerSample/8
// The number of bytes for one sample including
// all channels. I wonder what happens when
// this number isn't an integer?
q = RiffUtil:getShort( riff, 1 );
riff:BlockAlign = q[1];
If( riff:BlockAlign != 2 * 2, Throw( "not expected block align" ) );
//34 2 BitsPerSample 8 bits = 8, 16 bits = 16, etc.
q = RiffUtil:getShort( riff, 1 );
riff:BitsPerSample = q[1];
If( riff:BitsPerSample != 16, Throw( "not expected bits per sample" ) );
Show( riff:AudioFormat, riff:NumChannels, riff:SampleRate, riff:ByteRate, riff:BlockAlign, riff:BitsPerSample );
{dataOffset, dataLength} = riff:chunks["data"];
riff:offset = dataOffset;
nShorts = dataLength / 2;
result = Shape( RiffUtil:getShort( riff, nShorts ), nShorts / 2, 2 );
riff << delete;// the namespace
result; // return integers or... /32768;// return normalized +/- 1.0
);
大多数评论取自参考站点，描述了 WAV 文件是如何解析的。 此代码处理一种 WAV 格式并在格式错误时抛出。 （我只需要 16 位 44.1KHz 立体声。）当然，此函数在执行任何其他操作之前会调用另一个加载函数。
RiffUtil:load = Function( {filename}, {Default Local},
riff = New Namespace();
riff:data = Blob To Matrix( Load Text File( filename, BLOB ), "uint", 1, "big" );
riff:offset = 1;
If( RiffUtil:getString( riff ) != "RIFF", Throw( filename || " is not a valid wav (RIFF missing)" ) );
q = RiffUtil:getLong( riff, 1 );
riff:length = q[1];
If( RiffUtil:getString( riff ) != "WAVE", Throw( filename || " is not a valid wav (WAVE missing)" ) );
// walk the chunks and record their offsets
riff:chunks = Associative Array();
While( riff:offset < riff:length - 8,
chunkName = RiffUtil:getString( riff );
q = RiffUtil:GetLong( riff, 1 );
chunkLength = q[1];
riff:chunks[chunkName] = Eval List( {riff:offset, chunkLength} );
riff:offset += chunkLength;
);
riff;//return
);
此函数执行繁重工作的第一部分，将 blob 加载到内存中，验证 RIFF 标签，然后验证 WAVE 标签，然后查看 WAVE 数据内部以拆分出命名的子块。 然后，较早的函数对 fmt 和数据块进行更多繁重的工作。
RiffUtil:getString = Function( {riff},
{Default Local}, // return a 4-character id
four = riff:data[riff:offset + 0 :: riff:offset + 3];
riff:offset += 4;
Blob To Char( Matrix To Blob( four, "uint", 1, "big" ) );
);
getString 检索 4 个字节作为 JSL 字符串；其他函数获取 1-2 或 4 字节的数字。 riff:offset 是一个变量，用于跟踪要处理的下一个字节在 blob 中的当前位置。 请注意上面的“四”是如何分配给一个包含四个元素的矩阵，然后转换为一个 blob，然后再转换为一个字符串。 这是在没有循环的情况下完成的并且运行速度很快。 这是数字版本。
// these two transforms assist in the two's complement conversion; if the MSB is on
// ("negative") then also subtract maximum value
RiffUtil:transform2 = ((0 :: 127) * (256 ^ 1)) || ((128 :: 255) * (256 ^ 1) - (256 ^ 2));
RiffUtil:getShort = Function( {riff, n},
{Default Local},
chooser = riff:offset + ((0 :: n - 1) * 2);
little = riff:data[chooser];
biggest = riff:data[chooser + 1];
riff:offset += 2 * n;
little + RiffUtil:transform2[biggest + 1];
);
RiffUtil:transform4 = ((0 :: 127) * (256 ^ 3)) || ((128 :: 255) * (256 ^ 3) - (256 ^ 4));
RiffUtil:getLong = Function( {riff, n},
{Default Local},
chooser = riff:offset + ((0 :: n - 1) * 4);
little = riff:data[chooser];
big = riff:data[chooser + 1];
bigger = riff:data[chooser + 2];
biggest = riff:data[chooser + 3];
riff:offset += 4 * n;
little + big * (256) + bigger * (256 ^ 2) + RiffUtil:transform4[biggest + 1];
);
二进制补码是另一个主题。 稍后我们需要一个 wavWriter；这里是。 它对字符串和数字具有完全相反的功能。
// wav writer...44.1 kHz 16 bit stereo
RiffUtil:WavWriter = Function( {filename, mat},
{Default Local},
uints = N Rows( mat ) * N Cols( mat );
wav = New Namespace();
wav:mat = J( 44 + 2 * uints, 1, 0 ); // pre-allocate buffer
wav:offset = 1; // 1-based
// http://soundfile.sapp.org/doc/WaveFormat/
//JMP offset is 1-based, these are 0-based
//0 4 ChunkID Contains the letters "RIFF" in ASCII form
// (0x52494646 big-endian form).
RiffUtil:putString( wav, "RIFF" );
//4 4 ChunkSize 36 + SubChunk2Size, or more precisely:
// 4 + (8 + SubChunk1Size) + (8 + SubChunk2Size)
// This is the size of the rest of the chunk
// following this number. This is the size of the
// entire file in bytes minus 8 bytes for the
// two fields not included in this count:
// ChunkID and ChunkSize.
RiffUtil:putLong( wav, J( 1, 1, 36 + 2 * uints ) );
//8 4 Format Contains the letters "WAVE"
// (0x57415645 big-endian form).
RiffUtil:putString( wav, "WAVE" );
//
//The "WAVE" format consists of two subchunks: "fmt " and "data":
//The "fmt " subchunk describes the sound data's format:
//
//12 4 Subchunk1ID Contains the letters "fmt "
// (0x666d7420 big-endian form).
RiffUtil:putString( wav, "fmt " );
//16 4 Subchunk1Size 16 for PCM. This is the size of the
// rest of the Subchunk which follows this number.
RiffUtil:putLong( wav, [16] );
//20 2 AudioFormat PCM = 1 (i.e. Linear quantization)
// Values other than 1 indicate some
// form of compression.
RiffUtil:putShort( wav, [1] );
//22 2 NumChannels Mono = 1, Stereo = 2, etc.
RiffUtil:putShort( wav, [2] );
//24 4 SampleRate 8000, 44100, etc.
RiffUtil:putLong( wav, [44100] );
//28 4 ByteRate == SampleRate * NumChannels * BitsPerSample/8
RiffUtil:putLong( wav, [176400] );
//32 2 BlockAlign == NumChannels * BitsPerSample/8
// The number of bytes for one sample including
// all channels. I wonder what happens when
// this number isn't an integer?
RiffUtil:putShort( wav, [4] );
//34 2 BitsPerSample 8 bits = 8, 16 bits = 16, etc.
RiffUtil:putShort( wav, [16] );
// 2 ExtraParamSize if PCM, then doesn't exist
// X ExtraParams space for extra parameters
//
//The "data" subchunk contains the size of the data and the actual sound:
//
//36 4 Subchunk2ID Contains the letters "data"
// (0x64617461 big-endian form).
RiffUtil:putString( wav, "data" );
//40 4 Subchunk2Size == NumSamples * NumChannels * BitsPerSample/8
// This is the number of bytes in the data.
// You can also think of this as the size
// of the read of the subchunk following this
// number.
RiffUtil:putLong( wav, J( 1, 1, 2 * uints ) );
//44 * Data The actual sound data.
RiffUtil:putShort( wav, mat );
Open( Save Text File( filename, Matrix To Blob( wav:mat, "uint", 1, "big" ) ) );
wav << delete;
);
RiffUtil:putString = Function( {wav, txt},
{Default Local},
mat = Blob To Matrix( Char To Blob( txt ), "uint", 1, "big" );
len = N Rows( mat );
wav:mat[wav:offset + 0 :: wav:offset + len - 1] = mat;
wav:offset += len;
0;//return
);
// should longs in wav files ever go negative? what about > 2GB data blocks?
RiffUtil:putLong = Function( {wav, mat},
{Default Local},
//show(mat);
len = N Rows( mat ) * N Cols( mat );
biggest = Floor( mat / 256 ^ 3 );
mat -= biggest * 256 ^ 3;
bigger = Floor( mat / 256 ^ 2 );
mat -= bigger * 256 ^ 2;
big = Floor( mat / 256 );
mat -= big * 256;
little = mat;
wav:mat[wav:offset + 0 :: wav:offset + 4 * len - 1] = Shape( little || big || bigger || biggest, 1, 4 * len );
wav:offset += 4 * len;
);
RiffUtil:putShort = Function( {wav, mat},
{Default Local}, // mat has two stereo columns of -32k...+32k ints
mat[Loc( mat < 0 )] += 256 ^ 2; // two's complement: -1==65535 ... -32768 == 32768
len = N Rows( mat ) * N Cols( mat ); // len unsigned (or two's complement) 16-bit values (L+R)
mat = Shape( mat, len, 1 ); // now mat is a list of 16 bit samples, one per row
big = Floor( mat / 256 );
mat -= big * 256; // high bytes
little = mat; // low bytes
//show(nrows(mat),ncols(mat),wav:offset,len,nrows(wav:mat),ncols(wav:mat),nrows(little),ncols(little));
wav:mat[wav:offset + 0 :: wav:offset + 2 * len - 1] = Shape( little || big, 1, 2 * len );
wav:offset += 2 * len;
);
您可能已经注意到 riff<<
现在是加载笔记的时候了。 我将为笔记加载器 JSL 创建另一个名称空间以使其保持隔离。
noteLoader = New Namespace(
"noteLoader"
);
noteLoader:load1 = Function( {path, samples, firstnote},
{Default Local},
Show( path );
result = New Namespace();
result:notes = Associative Array();
temp = RiffUtil:loadWav( path );
For( pos = 1, pos < N Rows( temp ) - samples, pos += samples,
//show(firstnote,pos,pos+samples-1,nrows(temp),ncols(temp));
result:notes[firstnote] = temp[pos :: pos + samples - 1, 0];
firstnote += 1;
);
result; // return
);
“load1”做了我为这个项目确定的事情；随着项目的进展，“负载”逐渐下降。 load1 使用 wav 加载器获取音频数据矩阵，然后使用 samples 参数遍历数据并为单个音符创建一个较短音频数据矩阵的关联数组。 Firstnote 是（由我）分配给音符升序的数字。
还有一个作曲家名字空间；作曲家 JSL 知道如何在作品中添加音符。
composer = New Namespace(
"composer"
);
composer:create = Function( {seconds},
{Default Local},
composer:mat = J( seconds * 44100, 2, 0 );
composer:choirPad4 = noteLoader:load1( path || "choir1/choirPad4.wav", 44100 * 8, 36);
composer:guitarVarA = noteLoader:load1( path || "Guitar1/varA.wav", 44100 * 2, 12 );
composer:guitarVarB = noteLoader:load1( path || "Guitar1/varB.wav", 44100 * 2, 12 );
composer:guitarVarC = noteLoader:load1( path || "Guitar1/varC.wav", 44100 * 2, 12 );
composer:guitarVarD = noteLoader:load1( path || "Guitar1/varD.wav", 44100 * 2, 12 );
composer:percus = noteLoader:load1( path || "Drum1/percus.wav", 44100 * 2, 1 );
);
composer:compose = Function( {instrument, note, position, volume}, {Default Local},
position = Round( 1 + position * 44100 );
duration = N Rows( instrument:notes[note] );
composer:mat[position :: (position + duration - 1), 0] += (instrument:notes[note]) * volume;
);
composer:new = Function( {}, {Default Local},
composer:mat[0, 0] = 0
);
composer:limit = Function( {}, {},
N Rows( composer:mat )
);
composer:save = Function( {filename}, {Default Local},
x = Max( Abs( composer:mat ) );
composer:mat = (20000 / x) * composer:mat; // normalize to +/- 20,000 out of +/- 32767
RiffUtil:wavWriter( filename, composer:mat );
);
作曲家还知道如何重新开始（新）和完成（保存）。
这是 youtube 视频中的音频。 如果您获得 LMMS 的副本来制作 WAV 文件，则附件将大约（由于随机选择）复制它。 加载 LMMS 项目并导出。
