Working through how to read sound files into a Buffer and then looping it. When I run the script to create a Buffer and read a sound file into it, it succeeds, but when I create a SynthDef using that buffer (the second line of code here), it gives me the error Buffer UGen: no buffer data. It's drawing on the same bufnum, so I'm not sure what's going on.
b = Buffer.read(s, Platform.resourceDir +/+ "sounds/testing.wav");
c= SynthDef(\loopbuffer, {arg start=0, end=10000; Out.ar(0,Pan2.ar(BufRd.ar(1, 0, Phasor.ar(0, BufRateScale.kr(b.bufnum), start, end),0.0)))}).play(s);
Platform.resourceDir ++ "/sounds/testing.wav"
The ++ here means no space is inserted when concatenating.
BufRd.ar(b.numChannels, b.bufNum)
The missing b.bufNum is causing your error. The channels 0 through 3 are reserved for hardware in/outs.
Related
I have a device that sends serial data over a USB to COM port to my program at various speeds and lengths.
Within the data there is a chunk of several thousands bytes that starts and ends with special distinct code ('FDDD' for start, 'FEEE' for end).
Due to the stream's length, occasionally not all data is received in one piece.
What is the recommended way to combine all bytes into one message BEFORE parsing it?
(I took care of the buffer size, but have no control over the serial line quality, and can not use hardware control with USB)
Thanks
One possible way to accomplish this is to have something along these lines:
# variables
# buffer: byte buffer
# buffer_length: maximum number of bytes in the buffer
# new_char: char last read from the UART
# prev_char: second last char read from the UART
# n: index to the buffer
new_char := 0
loop forever:
prev_char := new_char
new_char := receive_from_uart()
# start marker
if prev_char = 0xfd and new_char = 0xdd
# set the index to the beginning of the buffer
n := 0
# end marker
else if prev_char = 0xfe and new_char = 0xee
# the frame is ready, do whatever you need to do with a complete message
# the length of the payload is n-1 bytes
handle_complete_message(buffer, n-1)
# otherwise
else
if n < buffer_length - 1
n := n + 1
buffer[n] := new_char
A few tips/comments:
you do not necessarily need a separate start and end markers (you can the same for both purposes)
if you want to have two-byte markers, it would be easier to have them with the same first byte
you need to make sure the marker combinations do no occur in your data stream
if you use escape codes to avoid the markers in your payload, it is convenient to take care of them in the same code
see HDLC asynchronous framing (simply to encode, simple to decode, takes care of the escaping)
handle_complete_message usually either copies the contents of buffer elsewhere or swaps another buffer instead of buffer if in hurry
if your data frames do not have integrity checking, you should check if the payload length is equal to buffer_length- 1, because then you may have an overflow
After several tests, I came up with the following simple solution to my own question (for c#).
Shown is a minimal simplified solution. Can add length checking, etc.
'Start' and 'End' are string markers of any length.
public void comPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
SerialPort port = (SerialPort)sender;
inData = port.ReadExisting();
{
if (inData.Contains("start"))
{
//Loop to collect all message parts
while (!inData.Contains("end"))
inData += port.ReadExisting();
//Complete by adding the last data chunk
inData += port.ReadExisting();
}
//Use your collected message
diaplaydata(inData);
My application has crashed in an assert, and the debugger is attached. To be able to reproduce the crash I want to save a C++ vector with 397 struct{uint64_t, uint64_t} elements to file.
My first approach was to try to print the vector. I can print the vector to the console, but it seems like only the first 256 values are written. Is it possible to remove the 256 element restriction?
I've also searched for a way to save the vector to file from within the debugger, but I've not found any way. I've not even found a way to save a memory region, but I guess that must be possible...
Since you mentioned that you're stopped in the debugger in Xcode, I'll assume you're debugging with lldb. You can use the expression command to execute essentially arbitrary code when you're stopped in the debugger, for example:
expression for(int j = 0; j < 10; j++) { (void)NSLog(#"%d", j); }
Will execute a for loop and print the numbers 0 through 9. You should be able to use a similar technique to iterate over your vector and write it to a file. You can combine multiple expressions using a semicolon, just as if you were writing normal code (well, except for newlines). For example, this will write "Hello, world" to a temporary file at /tmp/vector.dat, not exactly what you want, but I think you'll get the idea:
expression FILE *fp = (FILE*)fopen("/tmp/vector.dat", "w"); (void)fprintf(fp, "Hello, world!\n"); (void)fclose(fp);
I have a question regarding vertex buffers. How does one read the vertices from the vertex buffer in D3D11? I want to get a particular vertex's position for calculations, if this approach is wrong, how would one do it? The following code does not (obviously) work.
VERTEX* vert;
D3D11_MAPPED_SUBRESOURCE ms;
devcon->Map(pVBufferSphere, NULL, D3D11_MAP_READ, NULL, &ms);
vert = (VERTEX*) ms.pData;
devcon->Unmap(pVBufferSphere, NULL);
Thanks.
Where your code is wrong:
You asking GPU to give you an address to its memory(Map()),
Storing this adress (operator=()),
Then saying: "Thanks, I don't need it anymore" (Unmap()).
After unmap, you can't really say where your pointer now points. It can point to memory location where already allocated another stuff or at memory of your girlfriend's laptop (just kidding =) ).
You must copy data (all or it's part), not pointer in between Map() Unmap(): use memcopy, for loop, anything. Put it in array, std::vector, BST, everything.
Typical mistakes that newcomers can made here:
Not to check HRESULT return value from ID3D11DeviceContext::Map method. If map fails it can return whatever pointer it likes. Dereferencing such pointer leads to undefined behavior. So, better check any DirectX function return value.
Not to check D3D11 debug output. It can clearly say what's wrong and what to do in plain good English language (clearly better than my English =) ). So, you can fix bug almost instantly.
You can only read from ID3D11Buffer if it was created with D3D11_CPU_ACCESS_READ CPU access flag which means that you must also set D3D11_USAGE_STAGING usage fag.
How do we usualy read from buffer:
We don't use staging buffers for rendering/calculations: it's slow.
Instead we copy from main buffer (non-staging and non-readable by CPU) to staging one (ID3D11DeviceContext::CopyResource() or ID3D11DeviceContext::CopySubresourceRegion()), and then copying data to system memory (memcopy()).
We don't do this too much in release builds, it will harm performance.
There are two main real-life usages of staging buffers: debugging (see if buffer contains wrong data and fix some bug in algorithm) and reading final non-pixel data (for example if you calculating scientific data in Compute shader).
In most cases you can avoid staging buffers at all by well-designing your code. Think as if CPU<->GPU was connected only one way: CPU->GPU.
The following code only get the address of the mapped resource, you didn't read anything before Unmap.
vert = (VERTEX*) ms.pData;
If you want to read data from the mapped resource, first allocate enough memory, then use memcpy to copy the data, I don't know your VERTEX structure, so I suppose vert is void*, you can convert it yourself
vert = new BYTE[ms.DepthPitch];
memcpy(vert, ms.pData, ms.DepthPitch];
Drop's answer was helpful. I figured that the reason why I wasn't able to read the buffer was because I didn't have the CPU_ACCESS_FLAG set to D3D11_CPU_ACCESS_READ before. Here
D3D11_BUFFER_DESC bufferDesc;
ZeroMemory(&bufferDesc, sizeof(bufferDesc));
bufferDesc.ByteWidth = iNumElements * sizeof(T);
bufferDesc.Usage = D3D11_USAGE_DEFAULT;
bufferDesc.CPUAccessFlags = D3D11_CPU_ACCESS_READ | D3D11_CPU_ACCESS_WRITE;
bufferDesc.BindFlags = D3D11_BIND_UNORDERED_ACCESS | D3D11_BIND_SHADER_RESOURCE ;
bufferDesc.MiscFlags = D3D11_RESOURCE_MISC_BUFFER_STRUCTURED;
bufferDesc.StructureByteStride = sizeof(T);
And then to read data I did
const ID3D11Device& device = *DXUTGetD3D11Device();
ID3D11DeviceContext& deviceContext = *DXUTGetD3D11DeviceContext();
D3D11_MAPPED_SUBRESOURCE ms;
HRESULT hr = deviceContext.Map(g_pParticles, 0, D3D11_MAP_READ, 0, &ms);
Particle* p = (Particle*)malloc(sizeof(Particle*) * g_iNumParticles);
ZeroMemory(p, sizeof(Particle*) * g_iNumParticles);
memccpy(p, ms.pData, 0, sizeof(ms.pData));
deviceContext.Unmap(g_pParticles, 0);
delete[] p;
I agree it's a performance decline, I wanted to do this, just to be able to debug the values!
Thanks anyway! =)
I have a vimscript which needs to switch to a particular buffer. That buffer will be specified by either full path, partial path, or just its name.
For example:
I am in the directory /home/user/code and I have 3 vim buffers open foo.py src/foo.py and src/bar.py.
If the script was told to switch to buffer /home/user/code/foo.py it would switch to buffer foo.py.
If it were told to switch to user/code/src/foo.py it would switch to buffer src/foo.py
If it were told to switch to foo.py it would switch to buffer foo.py
If it were told to swith to bar.py it would switch to buffer src/bar.py
The simplest solution I can see is to somehow get a list of the buffers stored in a variable and use trial and error.
It would be nice if the solution was cross platform, but it needs to at least run on Linux.
The bufname() / bufnr() functions can lookup loaded buffers by partial filename. You can anchor the match to the end by appending a $, like this:
echo bufnr('/src/foo.py$')
I found a way to do this using python in a vimscript. With python I was able to get the names of all the buffers from vim.buffers[i].name and used os.path and os.sep to process which buffer to switch to.
In the end, I decided that it would be more helpful for it to refuse to do anything if the buffer it was requested to switch to was ambiguous.
Here it is:
"Given a file, full path, or partial path, this will try to change to the
"buffer which may match that file. If no buffers match, it returns 1. If
"multiple buffers match, it returns 2. It returns 0 on success
function s:GotoBuffer(buf)
python << EOF
import vim, os
buf = vim.eval("a:buf")
#split the paths into lists of their components and reverse.
#e.g. foo/bar/baz.py becomes ['foo', 'bar', 'baz.py']
buf_path = os.path.normpath(buf).split(os.sep)[::-1]
buffers = [os.path.normpath(b.name).split(os.sep)[::-1] for b in vim.buffers]
possible_buffers = range(len(buffers))
#start eliminating incorrect buffers by their filenames and paths
for component in xrange(len(buf_path)):
for b in buffers:
if len(b)-1 >= component and b[component] != buf_path[component]:
#This buffer doesn't match. Eliminate it as a posibility.
i = buffers.index(b)
if i in possible_buffers: possible_buffers.remove(i)
if len(possible_buffers) > 1: vim.command("return 2")
#delete the next line to allow ambiguous switching
elif not possible_buffers: vim.command("return 1")
else:
vim.command("buffer " + str(possible_buffers[-1] + 1))
EOF
endfunction
EDIT: The above code seems to have some bugs. I am not going to fix them because there is another answer which is much better.
I'm working on a DSP related iOS app. Part of the work is to copy audio data from outBuffer ->mAudioData to an user-specified array for data processing. The read method is like this:
OSStatus result = AudioFileReadPackets(myInfo->mAudioFile, // The audio file from which packets of audio data are to be read.
false, // Set to true to cache the data. Otherwise, set to false.
&numBytes, // On output, a pointer to the number of bytes actually returned.
myInfo->mPacketDescs, // A pointer to an array of packet descriptions that have been allocated.
myInfo->mCurrentPacket, // The packet index of the first packet you want to be returned.
&nPackets, // On input, a pointer to the number of packets to read. On output, the number of packets actually read.
outBuffer->mAudioData); // A pointer to user-allocated memory.
This process is successful. But when I'm trying to read data from outBuffer->mAudioData, there is always an error saying invalid conversion from 'void* const' to 'SInt16*':
outBuffer->mAudioDataByteSize = numBytes;
SInt16 *testBuffer = outBuffer->mAudioData; //Read data from buffer... Error!
for (int i=0; i<numBytes; i++)
{
UInt16 currentData = testBuffer[i];
printf("Current data in testbuffer is %d", currentData);
}
I have gone through several related questions like THIS and THIS, seems theirs are working...
I also tried to replace outBuffer->mAudioData to testBuffer in AudioFileReadPackets(), but the testBuffer turns out to be an empty array.
So is it the right approach? Is there any other way to read the raw data to an int/float array?
Or more generally, how to access an void constant pointer and perform read/write operation to it? (Yeah my C++ is not that strong...)
Any help will be appreciated :-)
Cheers,
Manca
I just put a cast in front and it seemed to work:
SInt16* frames = (SInt16*)inBuffer->mAudioData;