| WAV格式和FLAC都是无损吗?有什么区别 | 您所在的位置：网站首页 › wav和flac格式哪个好 › WAV格式和FLAC都是无损吗?有什么区别 |
|
WAV格式和FLAC格式都是无损，常见的无损格式有ape，wav，flac三种。 WAV格式和FLAC格式区别如下： 1、解析区别。FLAC与WAV都是无损压缩，也就是说音频以FLAC编码压缩后不会丢失任何信息，将FLAC文件还原为WAV文件后，与压缩前的WAV文件内容相同。WAV 格式容量过大，因而使用起来很不方便。 2、文件大小。WAV是最接近无损的音乐格式，所以文件大小相对也比较大。大多数情况下，一个WAV音频文件经压缩后得到的APE文件，一般会比压缩为FLAC文件稍微小一些。 3、容错能力。WAV文件的容错性差，而FLAC文件因为每帧数据之间无关联。因此当FLAC文件在传播过程中受损，导致某帧数据损坏缺失的话，只会损失该帧的音频信息唤悄，不会影响到前后的数据。这是FLAC的优势，但也因此FLAC的压缩率略低。 扩展资料： WAV 格式容量过大，因而使用起来很不方便。因此，一般情况下我们把它压缩为MP3或 WMA 格式。压缩方法有无损压缩，有损压缩，以及混成压缩。MPEG, JPEG就属于混成压缩，如果把压缩的数据还原回去，数据其实是不一样的。 如果把 MP3, OGG格式从压缩的状态还原回去的话，就会产生损失。然而， APE和FLAC格式即使还原，也能毫无损失地保留原有音质。所以， APE和FLAC可以无损失高音质地压缩和还原。在完全保持音质的前提下，APE的压缩容量有了适当的减小。 在特殊情况下，可以将FLAC文件视为一个光盘镜像，并加载到虚拟光驱上，这可以通过Nero将FLAC文和指渣件刻录到映像文件然后通过虚拟光驱加载来实现，也可以通过WinMount软件可以直接把Flac文件挂载到一个虚拟光驱。但是因为操作繁琐，所以除非在必要情逗档况下，一般我们都是通过播放软件直接播放的。 参考资料：百度百科_flac 百度百科_WAV 百度百科_无损音频 大小上：wavflacape WAV格式文件所占容量（B) = （取样频率 X量化位数X 声道） X 时间 / 8 (字节= 8bit) 每一分钟WAV格式的音频文件的大小为10MB，其大小不随音量大小及清晰度的变化而变化。WAV是最接近无损的音乐格式，所以文件大小相对也比较大。 FLAC是无损压缩，也就是说音频以FLAC编码压缩后不会丢失任何信息，将FLAC文件还原为WAV文件后，与压缩前的WAV文件内容相同。这种压缩与ZIP的方式类似顷亮，但FLAC的压缩比率大于ZIP和RAR，因为FLAC是专门针对PCM音频的特点设计的压缩方式。 相较同类文件格式FLAC，APE有查错能力但不提供纠错功能，以保证文件的无损和纯正；其另一个特色是压缩率约为55%，比FLAC高，体积大概为原CD的一半，便于存储。 扩展资料： 作为数字音乐文件格式的标准，WAV格式体积过大，一个3分左右的音乐文件30-50MB，使用起来很不方便。因此，一般情况下我们把它压缩为MP3等体积更小的缺乎昌格式。 常见的音频压缩方法有：无损压缩，有损压缩。其中，有损压缩是以破坏源文件数据方式（直接删除人耳听力范围之外的数字信息、甚至是删除部分人耳听力范围之内的信息，只保留基本声音）来换取小体积文件的，如常见的MP2、MP3、ogg、m4a、wma等等格式； 这种破坏是永久性的、不可逆的。稍加比较，你就能听出（如MP3）低于120K码率的文件和320K码率文件音质的天壤之别。但对于320K码率的音乐，由于其删除的只是人耳听力范围之外的信息，一般是难以与CD分辨的。 尽管如此，如果用高级音响设备放大播放的话，声音与CD还是有差的，毕竟是删除了数据的。无损压缩，顾名思义，就是只改变源文件数据记录方式，使其体积变小，它对元数据不作任何不可逆性地破坏。伏扒 目前常见的无损压缩数字音乐格式有：APE、FLAC等。 function [y,Fs,bits,opt_ck] = wavread(file,ext)nargchk(1,2,nargin) if nargin2, ext=[]end% Default - read all samples exts = numel(ext)% length of extent info if ~strncmpi(ext,'size',exts) (exts 2), error('Index range must be specified as a scalar or 2-element vector.') end if ~ischar(ext) exts==1, if ext==0, ext='size' % synonym for size else ext=[1 ext] % Prepend start sample index end end [fid,msg] = open_wav(file) error(msg) try [riffck,msg] = find_cktype(fid,'RIFF') if ~isempty(msg), error('Not a WAVE file.') end msg = check_rifftype(fid,'WAVE') error(msg) end_of_file = 0 opt_ck = [] while(~end_of_file), [ck,msg] = find_cktype(fid) error(msg) switch lower(ck.ID)
case 'end of file' end_of_file = 1
case 'fmt' % fmt-ckfound [opt_ck,msg] = read_wavefmt(fid,ck,opt_ck) error(msg) case 'data' % data-ckfound: if ~isfield(opt_ck,'fmt'), error('Corrupt WAV file: found audio data before format information.'此携宽) end
if strncmpi(ext,'size',exts) || ... (~isempty(ext) all(ext==0)), % Caller doesn't want data - just data size: [samples,msg] = read_wavedat(ck, opt_ck.fmt, -1) error(msg) y = [samples opt_ck.fmt.nChannels]
else % Read wave-data: [datack,msg] = read_wavedat(ck, opt_ck.fmt, ext) error(msg) y = datack.Data
end
case '森亮隐携fact' % Optional fact-ckfound: [opt_ck,msg] = read_factck(fid, ck, opt_ck) error(msg) case 'disp' % Optional disp-ckfound: [opt_ck,msg] = read_dispck(fid, ck, opt_ck) error(msg) case 'list' % Optional list-ckfound: [opt_ck, msg] = read_listck(fid, ck, opt_ck) error(msg)
otherwise % Skip over data in unprocessed chunks: if rem(ck.Size,2), ck.Size=ck.Size+1end if(fseek(fid,ck.Size,0)==-1), error('Incorrect chunk size information in WAV file.') end end end catch fclose(fid) error(lasterr) end fclose(fid) % Parse structure info for return to user: Fs = opt_ck.fmt.nSamplesPerSec if opt_ck.fmt.wFormatTag == 1 || opt_ck.fmt.wFormatTag == 3, % Type 3 floating point has no nBitsPerSample field, so use % nBlockAlign to figure out number of bits bits = (opt_ck.fmt.nBlockAlign / opt_ck.fmt.nChannels) * 8 else bits = [] % Unknown end % end of wavread() % ------------------------------------------------------------------------ % Local functions: % ------------------------------------------------------------------------ % --------------------------------------------- % OPEN_WAV: Open a WAV file for reading % --------------------------------------------- function [fid,msg] = open_wav(file) % Append .wav extension if it's missing: [pat,nam,ext] = fileparts(file) if isempty(ext), file = [file '.wav'] end [fid,msg] = fopen(file,'rb','l') % Little-endian if fid == -1, msg = 'Cannot open file.' end return % --------------------------------------------- % READ_CKINFO: Reads next RIFF chunk, but not the chunk data. % If optional sflg is set to nonzero, reads SUBchunk info instead. % Expects an open FID pointing to first byte of chunk header. % Returns a new chunk structure. % --------------------------------------------- function [ck,msg] = read_ckinfo(fid) msg = '' ck.fid = fid ck.Data = [] err_msg = 'Truncated chunk header found - possibly not a WAV file.' [s,cnt] = fread(fid,4,'char') % Do not error-out if a few (4) trailing chars are in file % Just return quickly: if (cnt~=4), if feof(fid), % End of the file (not an error) ck.ID = 'end of file' % unambiguous chunk ID (4 chars) ck.Size = 0 else msg = err_msg end return end ck.ID = deblank(char(s')) % Read chunk size (skip if subchunk): [sz,cnt] = fread(fid,1,'uint32') if cnt~=1, msg = err_msg return end ck.Size = sz return % --------------------------------------------- % FIND_CKTYPE: Finds a chunk with appropriate type. % Searches from current file position specified by fid. % Leaves file positions to data of desired chunk. % If optional sflg is set to nonzero, finds a SUBchunk instead. % --------------------------------------------- function [ck,msg] = find_cktype(fid,ftype) msg = '' if nargin2, ftype = ''end [ck,msg] = read_ckinfo(fid) if ~isempty(msg), returnend % Was a required chunk type specified? if ~isempty(ftype) ~strcmpi(ck.ID,ftype), msg = ['' ftype '-ckdid not appear as expected'] end return % --------------------------------------------- % CHECK_RIFFTYPE: Finds the RIFF data type. % Searches from current file position specified by fid. % Leaves file positions to data of desired chunk. % --------------------------------------------- function msg = check_rifftype(fid,ftype) msg = '' [rifftype,cnt] = fread(fid,4,'char') rifftype = char(rifftype)' if cnt~=4, msg = 'Not a WAVE file.' elseif ~strcmpi(rifftype,ftype), msg = ['File does not contain required ''' ftype ''' data chunk.'] end return % --------------------------------------------- % READ_LISTCK: Read the FLIST chunk: % --------------------------------------------- function [opt_ck,msg] = read_listck(fid,ck, orig_opt_ck) opt_ck = orig_opt_ck orig_pos= ftell(fid) total_bytes = ck.Size% # bytes in subchunk nbytes = 4 % # of required bytes in list-ckheader msg = '' err_msg = 'Error reading list-ckchunk.' if total_bytes nbytes, msg = err_msg return end % Read standard list-ckdata: listdata = char(fread(fid,total_bytes,'uchar')') listtype = lower(listdata(1:4))% Get LIST type listdata = listdata(5:end) % Move past INFO if strcmp(listtype,'info'), % Information: while(~isempty(listdata)), id = listdata(1:4) switch lower(id) case 'iart' name = 'Artist' case 'icmt' name = 'Comments' case 'icrd' name = 'Creation date' case 'icop' name = ['Copy' 'right'] case 'ieng' name = 'Engineer' case 'inam' name = 'Name' case 'iprd' name = 'Product' case 'isbj' name = 'Subject' case 'isft' name = 'Software' case 'isrc' name = 'Source' otherwise name = id end
if ~isfield(opt_ck,'info'), opt_ck.info = [] end len = listdata(5:8) * 2.^[0 8 16 24]' txt = listdata(9:9+len-1)
% Fix up text: deblank, and replace CR/LR with LF txt = deblank(txt) idx=findstr(txt,char([13 10])) txt(idx) = ''
% Store - don't include the "name" info opt_ck.info.(lower(id)) = txt
if rem(len,2), len=len+1end listdata = listdata(9+len:end) end
else if ~isfield(opt_ck,'list'), opt_ck.list = [] end opt_ck.list.(listtype) = listdata end % Skip over any unprocessed data: if rem(total_bytes,2), total_bytes=total_bytes+1end rbytes = total_bytes - (ftell(fid) - orig_pos) if rbytes~=0, if (fseek(fid,rbytes,'cof')==-1), msg = err_msg end end return % --------------------------------------------- % READ_DISPCK: Read the DISP chunk: % --------------------------------------------- function [opt_ck, msg] = read_dispck(fid,ck,orig_opt_ck) opt_ck = orig_opt_ck orig_pos= ftell(fid) total_bytes = ck.Size% # bytes in subchunk nbytes = 4 % # of required bytes in disp-ckheader msg = '' err_msg = 'Error reading disp-ckchunk.' if total_bytes nbytes, msg = err_msg return end % Read standard disp-ckdata: data = fread(fid,total_bytes,'uchar') % Process data: % First few entries are size info: icon_data = data siz_info = reshape(icon_data(1:2*4),4,2)' siz_info = siz_info*(2.^[0 8 16 24]') is_icon = isequal(siz_info,[840]) if ~is_icon, % Not the icon: opt_ck.disp.name = 'DisplayName' txt = deblank(char(data(5:end)')) opt_ck.disp.text = txt end % Skip over any unprocessed data: if rem(total_bytes,2), total_bytes=total_bytes+1end rbytes = total_bytes - (ftell(fid) - orig_pos) if rbytes~=0, if(fseek(fid,rbytes,'cof')==-1), msg = err_msg end end return % --------------------------------------------- % READ_FACTCK: Read the FACT chunk: % --------------------------------------------- function [opt_ck,msg] = read_factck(fid,ck,orig_opt_ck) opt_ck = orig_opt_ck orig_pos= ftell(fid) total_bytes = ck.Size% # bytes in subchunk nbytes = 4 % # of required bytes in fact-ckheader msg = '' err_msg = 'Error reading fact-ckchunk.' if total_bytes nbytes, msg = err_msg return end % Read standard fact-ckdata: opt_ck.fact = char(fread(fid,total_bytes,'uchar')') % Skip over any unprocessed data: if rem(total_bytes,2), total_bytes=total_bytes+1end rbytes = total_bytes - (ftell(fid) - orig_pos) if rbytes~=0, if(fseek(fid,rbytes,'cof')==-1), msg = err_msg end end return % --------------------------------------------- % READ_WAVEFMT: Read WAVE format chunk. % Assumes fid points to the wave-fmtsubchunk. % Requires chunk structure to be passed, indicating % the length of the chunk in case we don't recognize % the format tag. % --------------------------------------------- function [opt_ck,msg] = read_wavefmt(fid,ck,orig_opt_ck) opt_ck = orig_opt_ck orig_pos= ftell(fid) total_bytes = ck.Size% # bytes in subchunk nbytes = 14 % # of required bytes in wave-formatheader msg = '' err_msg = 'Error reading wave-fmtchunk.' if total_bytes nbytes, msg = err_msg return end % Read standard wave-formatdata: opt_ck.fmt.wFormatTag = fread(fid,1,'uint16')% Data encoding format opt_ck.fmt.nChannels = fread(fid,1,'uint16')% Number of channels opt_ck.fmt.nSamplesPerSec = fread(fid,1,'uint32') % Samples per second opt_ck.fmt.nAvgBytesPerSec = fread(fid,1,'uint32') % Avg transfer rate opt_ck.fmt.nBlockAlign = fread(fid,1,'uint16')% Block alignment % Read format-specific info: switch opt_ck.fmt.wFormatTag case 1 % PCM Format: [opt_ck.fmt, msg] = read_fmt_pcm(fid, ck, opt_ck.fmt) end % Skip over any unprocessed fmt-specific data: if rem(total_bytes,2), total_bytes=total_bytes+1end rbytes = total_bytes - (ftell(fid) - orig_pos) if rbytes~=0, if(fseek(fid,rbytes,'cof')==-1), msg = err_msg end end return % --------------------------------------------- % READ_FMT_PCM: Read PCM-format-specificinfo % --------------------------------------------- function [fmt,msg] = read_fmt_pcm(fid, ck, fmt) % There had better be a bits/sample field: total_bytes = ck.Size% # bytes in subchunk nbytes = 14 % # of bytes already read in wave-formatheader msg = '' err_msg = 'Error reading PCM wave-fmtchunk.' if (total_bytes nbytes+2), msg = err_msg return end [bits,cnt] = fread(fid,1,'uint16') nbytes=nbytes+2 if (cnt~=1), msg = err_msg return end fmt.nBitsPerSample=bits % Are there any additional fields present? if (total_bytes nbytes), % See if the "cbSize" field is present. If so, grab the data: if (total_bytes = nbytes+2), % we have the cbSize uint16 in the file: [cbSize,cnt]=fread(fid,1,'uint16') nbytes=nbytes+2 if (cnt~=1), msg = err_msg return end fmt.cbSize = cbSize end
% Simply skip any remaining stuff - we don't know what it is: if rem(total_bytes,2), total_bytes=total_bytes+1end rbytes = total_bytes - nbytes if rbytes~=0, if (fseek(fid,rbytes,'cof') == -1) msg = err_msg end end end return % --------------------------------------------- % READ_WAVEDAT: Read WAVE data chunk % Assumes fid points to the wave-data chunk % Requires data-ckand wave-formatstructures to be passed. % Requires extraction range to be specified. % Setting ext=[] forces ALL samples to be read. Otherwise, % ext should be a 2-element vector specifying the first % and last samples (per channel) to be extracted. % Setting ext=-1 returns the number of samples per channel, % skipping over the sample data. % --------------------------------------------- function [dat,msg] = read_wavedat(datack,wavefmt,ext) % In case of unsupported data compression format: dat = [] fmt_msg = '' switch wavefmt.wFormatTag case 1 % PCM Format: [dat,msg] = read_dat_pcm(datack,wavefmt,ext) case 2 fmt_msg = 'Microsoft ADPCM' case 3 % normalized floating-point [dat,msg] = read_dat_pcm(datack,wavefmt,ext) case 6 fmt_msg = 'CCITT a-law' case 7 fmt_msg = 'CCITT mu-law' case 17 fmt_msg = 'IMA ADPCM' case 34 fmt_msg = 'DSP Group TrueSpeech TM' case 49 fmt_msg = 'GSM 6.10' case 50 fmt_msg = 'MSN Audio' case 257 fmt_msg = 'IBM Mu-law' case 258 fmt_msg = 'IBM A-law' case 259 fmt_msg = 'IBM AVC Adaptive Differential' otherwise fmt_msg = ['Format #' num2str(wavefmt.wFormatTag)] end if ~isempty(fmt_msg), msg = ['Data compression format (' fmt_msg ') is not supported.'] end return % --------------------------------------------- % READ_DAT_PCM: Read PCM format data from wave-datachunk. % Assumes fid points to the wave-data chunk % Requires data-ckand wave-formatstructures to be passed. % Requires extraction range to be specified. % Setting ext=[] forces ALL samples to be read. Otherwise, % ext should be a 2-element vector specifying the first % and last samples (per channel) to be extracted. % Setting ext=-1 returns the number of samples per channel, % skipping over the sample data. % --------------------------------------------- function [dat,msg] = read_dat_pcm(datack,wavefmt,ext) dat = [] msg = '' % Determine # bytes/sample - format requires rounding % to next integer number of bytes: BytesPerSample = ceil(wavefmt.nBlockAlign / wavefmt.nChannels) if (BytesPerSample == 1), dtype='uchar'% unsigned 8-bit elseif (BytesPerSample == 2), dtype='int16'% signed 16-bit elseif (BytesPerSample == 3) dtype='bit24'% signed 24-bit elseif (BytesPerSample == 4), % 32-bit 16.8 float (type 1 - 32-bit) % 32-bit normalized floating point dtype = 'float' % 32-bit 24.0 float (type 1 - 24-bit) if wavefmt.wFormatTag ~= 3 wavefmt.nBitsPerSample == 24, BytesPerSample = 3 end else msg = 'Cannot read PCM file formats with more than 32 bits per sample.' return end total_bytes = datack.Size% # bytes in this chunk total_samples = total_bytes / BytesPerSample SamplesPerChannel = total_samples / wavefmt.nChannels if ~isempty(ext) isscalar(ext) ext==-1 % Just return the samples per channel, and fseek past data: dat = SamplesPerChannel % Add in a pad-byte, if required: total_bytes = total_bytes + rem(datack.Size,2) if(fseek(datack.fid,total_bytes,'cof')==-1), msg = 'Error reading PCM file format.' end return end % Determine sample range to read: if isempty(ext), ext = [1 SamplesPerChannel] % Return all samples else if numel(ext)~=2, msg = 'Sample limit vector must have 2 elements.' return end if ext(1)1 || ext(2)SamplesPerChannel, msg = 'Sample limits out of range.' return end if ext(1)ext(2), msg = 'Sample limits must be given in ascending order.' return end end bytes_remaining = total_bytes % Preset byte counter % Skip over leading samples: if ext(1)1, % Skip over leading samples, if specified: skipcnt = BytesPerSample * (ext(1)-1) * wavefmt.nChannels if(fseek(datack.fid, skipcnt,'cof') == -1), msg = 'Error reading PCM file format.' return end % % Update count of bytes remaining: bytes_remaining = bytes_remaining - skipcnt end % Read desired data: nSPCext= ext(2)-ext(1)+1% # samples per channel in extraction range dat= datack % Copy input structure to output % extSamples = wavefmt.nChannels*nSPCext dat.Data = fread(datack.fid, [wavefmt.nChannels nSPCext], dtype) % % Update count of bytes remaining: skipcnt = BytesPerSample*nSPCext*wavefmt.nChannels bytes_remaining = bytes_remaining - skipcnt % if cnt~=extSamples, dat='Error reading file.'returnend % Skip over trailing samples: if(fseek(datack.fid, BytesPerSample * ... (SamplesPerChannel-ext(2))*wavefmt.nChannels, 'cof')==-1), msg = 'Error reading PCM file format.' return end % Update count of bytes remaining: skipcnt = BytesPerSample*(SamplesPerChannel-ext(2))*wavefmt.nChannels bytes_remaining = bytes_remaining - skipcnt % Determine if a pad-byte is appended to data chunk, % skipping over it if present: if rem(datack.Size,2), fseek(datack.fid, 1, 'cof') end % Rearrange data into a matrix with one channel per column: dat.Data = dat.Data' % Normalize data range: min will hit -1, max will not quite hit +1. if BytesPerSample==1, dat.Data = (dat.Data-128)/128 % [-1,1) elseif BytesPerSample==2, dat.Data = dat.Data/32768 % [-1,1) elseif BytesPerSample==3, dat.Data = dat.Data/(2^23)% [-1,1) elseif BytesPerSample==4, if wavefmt.wFormatTag ~= 3,% Type 3 32-bit is already normalized dat.Data = dat.Data/32768% [-1,1) end end return % end of wavread.m 欢迎分享，转载请注明来源：内存溢出 原文地址:https://outofmemory.cn/tougao/8184343.html |
| CopyRight 2018-2019 实验室设备网 版权所有 |