mpv_ipc_issue.c

// MPV test
//
// mpv stops responding after about 50 loadfile commands are written, however writefile can keep
// writing even after mpv stops responding to commands
// mpv starts responding after this program is forced to quit/the pipe disconnects
// If you open pipe, write, then close pipe every command, this problem does not occur.
//
// You can validate this behavior by opening mpv in command line mode with -v and seeing
// that the output stops after some time. MPV wil still respond to keyboard commands though

#include <Windows.h>
#include "stdio.h"

int main()
{
    //const char command[] = "loadfile sdfasdfsadfasdfasdfc.mp3\n";     //doesn't matter if file doesn't exist
    const char command[] = "loadfile test.mp3\n";
    //const char command[] = "loadfile movie.mpg\n";

    HANDLE hPipe = CreateFile(L"\\\\.\\pipe\\mpvsocket", GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
    if (hPipe == INVALID_HANDLE_VALUE)
    {
        return 0;   //exit if can't create pipe
    }

    unsigned int total_bytes_written = 0;

    for (int i = 0; i < 1000; i++)
    {
        DWORD dwWritten;
        BOOL fSuccess = WriteFile(hPipe, command, sizeof(command)-1, &dwWritten, NULL);
        if (!fSuccess)
        {
            break; //exit if write fails
        }

        total_bytes_written += dwWritten;
        printf("%d: wrote %d bytes, total: %d\n", i, dwWritten, total_bytes_written);

        //FlushFileBuffers(hPipe);
        Sleep(300); //timing doesn't seem to make any difference, just takes longer to cause the problem.
    }

    CloseHandle(hPipe);

    return 0;
}