使用libsox将音频转换为FLAC

我正在尝试使用libSoX API以编程方式在内存缓冲区中转换音频。例如，它可以很好地改变采样率，但是PCM和FLAC之间的转换有一定的麻烦。使用libsox将音频转换为FLAC

QByteArray inData = [...]; 
sox_effect_t *e; 
char *args[10]; 

sox_globals.output_message_handler = output_message; 
sox_globals.verbosity = 4; 

assert(sox_init() == SOX_SUCCESS); 

sox_signalinfo_t in_signal_info; 
in_signal_info.channels = numChannels; 
in_signal_info.length = numSamples * numChannels; 
in_signal_info.precision = precision; 
in_signal_info.rate = sampleRate; 
in_signal_info.mult = NULL; 

sox_encodinginfo_t in_encoding_info; 
in_encoding_info.bits_per_sample = bitsPerSample; 
in_encoding_info.encoding = SOX_ENCODING_SIGN2; 

in_encoding_info.reverse_bytes = sox_option_no; 
in_encoding_info.reverse_bits = sox_option_no; 
in_encoding_info.opposite_endian = sox_false; 
in_encoding_info.reverse_nibbles = sox_option_no; 

sox_format_t *in = 
    sox_open_mem_read(inData, inData.size(), 
         &in_signal_info, &in_encoding_info, "raw"); 

sox_format_t *out_format = (sox_format_t *)malloc(sizeof(sox_format_t)); 
memcpy(out_format, in, sizeof(sox_format_t)); 
out_format->encoding.encoding = SOX_ENCODING_FLAC; 

char *outbuffer; 
size_t outbuffer_size; 
sox_format_t *out = sox_open_memstream_write(&outbuffer, &outbuffer_size, 
              &out_format->signal, 
              &out_format->encoding, "flac", NULL); 

sox_effects_chain_t *chain = 
sox_create_effects_chain(&in->encoding, &out->encoding); 

e = sox_create_effect(sox_find_effect("input")); 
args[0] = (char *)in; 
assert(sox_effect_options(e, 1, args) == SOX_SUCCESS); 
assert(sox_add_effect(chain, e, &in->signal, &in->signal) == SOX_SUCCESS); 
free(e); 

e = sox_create_effect(sox_find_effect("output")); 
args[0] = (char *)out; 
assert(sox_effect_options(e, 1, args) == SOX_SUCCESS); 
assert(sox_add_effect(chain, e, &in->signal, &out->signal) == SOX_SUCCESS); 
free(e); 

sox_flow_effects(chain, NULL, NULL); 
sox_delete_effects_chain(chain); 
sox_close(out); 
free(out_format); 
free(outbuffer); 
sox_close(in);

输出我得到：

DBUG formats: opening format plugin `lsx_flac_format_fn': library 0x1075ee0, entry point 0x7f3258eee5c0 
FAIL formats: can't open output file `': FLAC compression level must be a whole number from 0 to 8 
demo_sox: main.cpp:120: int main(int, char **): Assertion `sox_effect_options(e, 1, args) == SOX_SUCCESS' failed.

它未能于：

e = sox_create_effect(sox_find_effect("output")); 
args[0] = (char *)out; 
assert(sox_effect_options(e, 1, args) == SOX_SUCCESS);

有几乎LibSoX使用没有文档，我在做它正确吗？

来源

2016-09-27 Dmytro Prylipko

答案是指定输出格式FLAC的压缩级别：

out_format->encoding.encoding = SOX_ENCODING_FLAC; 
out_format->encoding.compression = 8;

来源

2016-09-27 12:47:06

使用libsox将音频转换为FLAC

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