gusucode.com > audiovideo工具箱matlab源码程序 > audiovideo/@VideoReader/VideoReader.m
classdef (CaseInsensitiveProperties=true, TruncatedProperties=true) ...
VideoReader < hgsetget & matlab.mixin.CustomDisplay
% VIDEOREADER Create a multimedia reader object.
%
% OBJ = VIDEOREADER(FILENAME) constructs a multimedia reader object, OBJ, that
% can read in video data from a multimedia file. FILENAME is a string
% specifying the name of a multimedia file. There are no restrictions
% on file extensions. By default, MATLAB looks for the file FILENAME on
% the MATLAB path.
%
% OBJ = VIDEOREADER(FILENAME, 'P1', V1, 'P2', V2, ...)
% constructs a multimedia reader object, assigning values V1, V2, etc. to
% the specified properties P1, P2, etc. Note that the property value
% pairs can be in any format supported by the SET function, e.g.
% parameter-value string pairs, structures, or parameter-value cell array
% pairs.
%
% Methods:
% readFrame - Read the next available frame from a video file.
% hasFrame - Determine if there is a frame available to read
% from a video file.
% getFileFormats - List of known supported video file formats.
%
% Properties:
% Name - Name of the file to be read.
% Path - Path of the file to be read.
% Duration - Total length of file in seconds.
% CurrentTime - Location from the start of the file of the current
% frame to be read in seconds.
% Tag - Generic string for the user to set.
% UserData - Generic field for any user-defined data.
%
% Height - Height of the video frame in pixels.
% Width - Width of the video frame in pixels.
% BitsPerPixel - Bits per pixel of the video data.
% VideoFormat - Video format as it is represented in MATLAB.
% FrameRate - Frame rate of the video in frames per second.
%
% Example:
% % Construct a multimedia reader object associated with file
% % 'xylophone.mp4'.
% vidObj = VideoReader('xylophone.mp4');
%
% % Specify that reading should start at 0.5 seconds from the
% % beginning.
% vidObj.CurrentTime = 0.5;
%
% % Create an axes
% currAxes = axes;
%
% % Read video frames until available
% while hasFrame(vidObj)
% vidFrame = readFrame(vidObj);
% image(vidFrame, 'Parent', currAxes);
% currAxes.Visible = 'off';
% pause(1/vidObj.FrameRate);
% end
%
% See also AUDIOVIDEO, VIDEOREADER/READFRAME, VIDEOREADER/HASFRAME, MMFILEINFO.
%
% Authors: NH DL
% Copyright 2005-2015 The MathWorks, Inc.
%------------------------------------------------------------------
% General properties (in alphabetic order)
%------------------------------------------------------------------
properties(GetAccess='public', SetAccess='private', Dependent)
Duration % Total length of file in seconds.
Name % Name of the file to be read.
Path % Path of the file to be read.
end
properties(GetAccess='public', SetAccess='public')
Tag = ''; % Generic string for the user to set.
end
properties(GetAccess='public', SetAccess='public')
UserData % Generic field for any user-defined data.
end
%------------------------------------------------------------------
% Video properties (in alphabetic order)
%------------------------------------------------------------------
properties(GetAccess='public', SetAccess='private', Dependent)
BitsPerPixel % Bits per pixel of the video data.
FrameRate % Frame rate of the video in frames per second.
Height % Height of the video frame in pixels.
VideoFormat % Video format as it is represented in MATLAB.
Width % Width of the video frame in pixels.
end
properties(Access='public', Dependent)
CurrentTime % Location, in seconds, from the start of the
% file of the current frame to be read.
end
%------------------------------------------------------------------
% Undocumented properties
%------------------------------------------------------------------
properties(GetAccess='public', SetAccess='private', Dependent, Hidden)
AudioCompression
NumberOfAudioChannels
VideoCompression
% NUMBEROFFRAMES property will be removed in a future release. Use
% CURRENTTIME property instead.
NumberOfFrames % Total number of frames in the video stream.
end
%------------------------------------------------------------------
% Private properties
%------------------------------------------------------------------
properties(Access='private', Hidden)
% To help support future forward compatibility.
SchemaVersion = 8.3;
% To handle construction on load.
LoadArgs
end
properties(Access='private', Hidden, Transient)
% Underlying implementation object.
VideoReaderImpl
% Enable frame counting
% This property will be removed as it is no longer relevant.
EnableFrameCounting;
% Flag to determine if frame-based operations are being performed
% on the file.
% Once frame-based operations have been enabled, time-based
% operations are not permitted.
IsFrameBased = false;
% Flag to determine if frame counting has been performed.
% This is used avoid counting of frames during every query of
% NumberOfFrames property.
IsFramesCounted = false;
% Flag to determine if time-based operations are being performed
% on the file.
% Once time-based operations have been enabled, frame-based
% operations are not permitted.
IsStreamingBased = false;
end
%------------------------------------------------------------------
% Documented methods
%------------------------------------------------------------------
methods(Access='public')
%------------------------------------------------------------------
% Lifetime
%------------------------------------------------------------------
function obj = VideoReader(fileName, varargin)
% If no file name provided.
if nargin == 0
error(message('MATLAB:audiovideo:VideoReader:noFile'));
end
try
validateattributes(fileName, {'char'}, {'row', 'vector'}, 'VideoReader');
catch ME
throwAsCaller(ME);
end
% Initialize the object.
% The duration of the file needs to be determined before the
% CurrentTime can be set.
obj.init(fileName);
% Set properties that user passed in.
if nargin > 1
set(obj, varargin{:});
end
end
%------------------------------------------------------------------
% Operations
%------------------------------------------------------------------
inspect(obj)
varargout = readFrame(obj, varargin)
eof = hasFrame(obj)
%------------------------------------------------------------------
% Overrides of builtins
%------------------------------------------------------------------
c = horzcat(varargin)
c = vertcat(varargin)
c = cat(varargin)
end
methods(Access='public', Hidden)
varargout = read(obj, varargin)
end
methods(Static)
%------------------------------------------------------------------
% Operations
%------------------------------------------------------------------
function formats = getFileFormats()
% GETFILEFORMATS
%
% FORMATS = VIDEOREADER.GETFILEFORMATS() returns an object
% array of audiovideo.FileFormatInfo objects which are the
% formats VIDEOREADER is known to support on the current
% platform.
%
% The properties of an audiovideo.FileFormatInfo object are:
%
% Extension - The file extension for this file format
% Description - A text description of the file format
% ContainsVideo - The File Format can hold video data
% ContainsAudio - The File Format can hold audio data
%
extensions = audiovideo.mmreader.getSupportedFormats();
formats = audiovideo.FileFormatInfo.empty();
for ii=1:length(extensions)
formats(ii) = audiovideo.FileFormatInfo( extensions{ii}, ...
VideoReader.translateDescToLocale(extensions{ii}), ...
true, ...
false );
end
% sort file extension
[~, sortedIndex] = sort({formats.Extension});
formats = formats(sortedIndex);
end
end
methods(Static, Hidden)
%------------------------------------------------------------------
% Persistence
%------------------------------------------------------------------
obj = loadobj(B)
end
%------------------------------------------------------------------
% Custom Getters/Setters
%------------------------------------------------------------------
methods
% Properties that are not dependent on underlying object.
function set.Tag(obj, value)
validateattributes( value, {'char'}, {}, 'set', 'Tag');
obj.Tag = value;
end
% Properties that are dependent on underlying object.
function value = get.Duration(obj)
try
value = obj.getImplValue('Duration');
catch exception
VideoReader.handleImplException(exception);
end
% Duration property is set to empty if it cannot be determined
% from the video. Generate a warning to indicate this.
if isempty(value)
warnState=warning('off','backtrace');
c = onCleanup(@()warning(warnState));
warning(message('MATLAB:audiovideo:VideoReader:unknownDuration'));
end
end
function set.Duration(obj, value)
obj.errorAsNotSettable('Duration', value);
end
function value = get.Name(obj)
value = obj.getImplValue('Name');
end
function set.Name(obj, value)
obj.errorAsNotSettable('Name', value);
end
function value = get.Path(obj)
value = obj.getImplValue('Path');
end
function set.Path(obj, value)
obj.errorAsNotSettable('Path', value);
end
function value = get.BitsPerPixel(obj)
value = obj.getImplValue('BitsPerPixel');
end
function set.BitsPerPixel(obj, value)
obj.errorAsNotSettable('BitsPerPixel', value);
end
function value = get.FrameRate(obj)
value = obj.getImplValue('FrameRate');
end
function set.FrameRate(obj, value)
obj.errorAsNotSettable('FrameRate', value);
end
function value = get.Height(obj)
value = obj.getImplValue('Height');
end
function set.Height(obj, value)
obj.errorAsNotSettable('Height', value);
end
function value = get.NumberOfFrames(obj)
if obj.IsStreamingBased
error( message('MATLAB:audiovideo:VideoReader:GetNumFramesNotAllowed') );
end
% If the video has been scanned to count the number of frames,
% do no repeat the operaton.
if ~obj.IsFramesCounted
obj.populateNumFrames();
obj.IsFramesCounted = true;
end
value = obj.getImplValue('NumberOfFrames');
% NumberOfFrames property is set to empty if it cannot be
% determined by from the video. Generate a warning in this
% case.
if isempty(value)
warnState=warning('off','backtrace');
c = onCleanup(@()warning(warnState));
warning(message('MATLAB:audiovideo:VideoReader:unknownNumFrames'));
end
end
function set.NumberOfFrames(obj, value)
obj.errorAsNotSettable('NumberOfFrames', value);
end
function value = get.VideoFormat(obj)
value = obj.getImplValue('VideoFormat');
end
function set.VideoFormat(obj, value)
obj.errorAsNotSettable('VideoFormat', value);
end
function value = get.Width(obj)
value = obj.getImplValue('Width');
end
function set.Width(obj, value)
obj.errorAsNotSettable('Width', value);
end
function value = get.AudioCompression(obj)
value = obj.getImplValue('AudioCompression');
end
function set.AudioCompression(obj, value)
obj.errorAsNotSettable('AudioCompression', value);
end
function value = get.NumberOfAudioChannels(obj)
value = obj.getImplValue('NumberOfAudioChannels');
end
function set.NumberOfAudioChannels(obj, value)
obj.errorAsNotSettable('NumberOfAudioChannels', value);
end
function value = get.VideoCompression(obj)
value = obj.getImplValue('VideoCompression');
end
function set.VideoCompression(obj, value)
obj.errorAsNotSettable('VideoCompression', value);
end
function value = get.CurrentTime(obj)
try
value = obj.getImplValue('CurrentTime');
catch ME
VideoReader.handleImplException(ME);
end
end
function set.CurrentTime(obj, value)
if obj.IsFrameBased
error( message('MATLAB:audiovideo:VideoReader:SetCurrentTimeNotAllowed') );
end
% Check that the duration of the file is known.
if ~isempty(obj.Duration)
try
validateattributes( value, {'double'}, ...
{'scalar', 'nonnegative', '<=', obj.Duration}, ...
'set', 'CurrentTime');
catch ME
throwAsCaller(ME);
end
end
currentTimeOC = onCleanup( @() set(obj, 'IsStreamingBased', 'true') );
try
obj.getImpl().CurrentTime = value;
catch exception
VideoReader.handleImplException(exception);
end
end
end
%------------------------------------------------------------------
% Overrides for Custom Display
%------------------------------------------------------------------
methods (Access='protected')
function propGroups = getPropertyGroups(~)
import matlab.mixin.util.PropertyGroup;
propGroups(1) = PropertyGroup( {'Name', 'Path', 'Duration', 'CurrentTime', 'Tag', 'UserData'}, ...
getString( message('MATLAB:audiovideo:VideoReader:GeneralProperties') ) );
propGroups(2) = PropertyGroup( {'Width', 'Height', 'FrameRate', 'BitsPerPixel', 'VideoFormat'}, ...
getString( message('MATLAB:audiovideo:VideoReader:VideoProperties') ) );
end
end
%------------------------------------------------------------------
% Overrides for Custom Display when calling get(vidObj)
%------------------------------------------------------------------
methods (Hidden)
function getdisp(obj)
display(obj);
end
end
%------------------------------------------------------------------
% Undocumented methods
%------------------------------------------------------------------
methods (Access='public', Hidden)
%------------------------------------------------------------------
% Lifetime
%------------------------------------------------------------------
function delete(obj)
% Delete VideoReader object.
try
delete(obj.getImpl());
catch exception
VideoReader.handleImplException( exception );
end
end
%------------------------------------------------------------------
% Operations
%------------------------------------------------------------------
function result = hasAudio(obj)
try
result = hasAudio(obj.getImpl());
catch exception
VideoReader.handleImplException( exception );
end
end
function result = hasVideo(obj)
try
result = hasVideo(obj.getImpl());
catch exception
VideoReader.handleImplException( exception );
end
end
end
methods (Static, Access='public', Hidden)
function handleImplException(implException)
messageArgs = { implException.identifier };
if (~isempty(implException.message))
messageArgs{end+1} = implException.message;
end
msgObj = message(messageArgs{:});
throwAsCaller(MException(implException.identifier, '%s',msgObj.getString));
end
end
methods (Static, Access='private', Hidden)
function errorIfImageFormat( fileName )
isImageFormat = false;
try
% see if imfinfo recognizes this file as an image
imfinfo( fileName );
isImageFormat = true;
catch exception %#ok<NASGU>
% imfinfo does not recognize this file, don't error
% since it is most likely a valid multimedia file
end
if isImageFormat
% If imfinfo does not error, then show this error
error(message('MATLAB:audiovideo:VideoReader:unsupportedImage'));
end
end
function errorIfTextFormat(fileName)
%Don't try to open text files with known text extensions.
[~,~,ext] = fileparts(fileName);
textExts = {'txt','text','csv','html','xml','m'};
if ~isempty(ext) && any(strcmpi(ext(2:end),textExts))
error(message('MATLAB:audiovideo:VideoReader:unsupportedText'));
end
end
function fileDesc = translateDescToLocale(fileExtension)
switch upper(fileExtension)
case 'M4V'
fileDesc = getString(message('MATLAB:audiovideo:VideoReader:formatM4V'));
case 'MJ2'
fileDesc = getString(message('MATLAB:audiovideo:VideoReader:formatMJ2'));
case 'MOV'
fileDesc = getString(message('MATLAB:audiovideo:VideoReader:formatMOV'));
case 'MP4'
fileDesc = getString(message('MATLAB:audiovideo:VideoReader:formatMP4'));
case 'MPG'
fileDesc = getString(message('MATLAB:audiovideo:VideoReader:formatMPG'));
case 'OGV'
fileDesc = getString(message('MATLAB:audiovideo:VideoReader:formatOGV'));
case 'WMV'
fileDesc = getString(message('MATLAB:audiovideo:VideoReader:formatWMV'));
otherwise
% This includes formats such as AVI, ASF, ASX.
fileDesc = getString(message('MATLAB:audiovideo:VideoReader:formatGeneric', upper(fileExtension)));
end
end
function outputFormat = validateOutputFormat(outputFormat, callerFcn)
validFormats = {'native', 'default'};
outputFormat = validatestring( outputFormat, validFormats, callerFcn,'outputformat');
end
function outputFrames = convertToOutputFormat( inputFrames, inputFormat, outputFormat, colormap)
switch outputFormat
case 'default'
outputFrames = VideoReader.convertToDefault(inputFrames, inputFormat, colormap);
case 'native'
outputFrames = VideoReader.convertToNative(inputFrames, inputFormat, colormap);
otherwise
assert(false, 'Unexpected outputFormat %s', outputFormat);
end
end
function outputFrames = convertToDefault(inputFrames, inputFormat, colormap)
if ~ismember(inputFormat, {'Indexed', 'Grayscale'})
% No conversion necessary, return the native data
outputFrames = inputFrames;
return;
end
% Return 'Indexed' data as RGB24 when asking for
% the 'Default' output. This is done to preserve
% RGB24 compatibility for customers using versions of
% VideoReader prior to R2013a.
outputFrames = zeros(size(inputFrames), 'uint8');
if strcmp(inputFormat, 'Grayscale')
for ii=1:size(inputFrames, 4)
% Indexed to Grayscale Image conversion (ind2gray) is part of IPT
% and not base-MATLAB.
tempFrame = ind2rgb( inputFrames(:,:,:,ii), colormap);
outputFrames(:,:,ii) = tempFrame(:, :, 1);
end
else
outputFrames = repmat(outputFrames, [1, 1, 3, 1]);
for ii=1:size(inputFrames, 4)
outputFrames(:,:,:,ii) = ind2rgb( inputFrames(:,:,:,ii), colormap);
end
end
end
function outputFrames = convertToNative(inputFrames, inputFormat, colormap)
if ~ismember(inputFormat, {'Indexed', 'Grayscale'})
% No conversion necessary, return the native data
outputFrames = inputFrames;
return;
end
% normalize the colormap
colormap = double(colormap)/255;
numFrames = size(inputFrames, 4);
outputFrames(1:numFrames) = struct;
for ii = 1:numFrames;
outputFrames(ii).cdata = inputFrames(:,:,:,ii);
outputFrames(ii).colormap = colormap;
end
end
end
%------------------------------------------------------------------
% Helpers
%------------------------------------------------------------------
methods (Access='private', Hidden)
function init(obj, fileName, varargin)
% Properly initialize the object on construction or load.
currentTime = [];
if nargin == 3
assert( isa(varargin{1}, 'double') && isscalar(varargin{1}), 'Last input argument is the current time');
currentTime = varargin{1};
end
% Expand the path, using the matlab path if necessary
fullName = audiovideo.internal.absolutePathForReading(...
fileName, ...
'MATLAB:audiovideo:VideoReader:FileNotFound', ...
'MATLAB:audiovideo:VideoReader:FilePermissionDenied');
VideoReader.errorIfImageFormat(fullName);
VideoReader.errorIfTextFormat(fullName);
% Create underlying implementation.
try
obj.VideoReaderImpl = audiovideo.mmreader(fullName);
catch exception
VideoReader.handleImplException( exception );
end
if ~isempty(currentTime)
obj.CurrentTime = currentTime;
end
end
function populateNumFrames(obj)
try
if ~obj.IsFrameBased
populateNumFrames(obj.getImpl());
obj.IsFrameBased = true;
else
return;
end
catch exception
VideoReader.handleImplException( exception );
end
end
function impl = getImpl(obj)
impl = obj.VideoReaderImpl;
end
function value = getImplValue(obj, propName)
value = obj.getImpl().(propName);
end
function errorAsNotSettable(obj, propName, value) %#ok<INUSD>
% All underlying properties are read only. Make the error
% the same as a standard MATLAB error when setting externally.
% TODO: Remove when g449420 is done and used when calling
% set() in the constructor.
err = MException('MATLAB:class:SetProhibited',...
'Setting the ''%s'' property of the ''%s'' class is not allowed.',...
propName, class(obj));
throwAsCaller(err);
end
function [headings, indices] = getCategoryInfo(obj, propNames)
% Returns headings and property indices for each category.
headings = {'General Settings' 'Video Settings', 'Audio Settings'};
indices = {[] [] []};
for pi=1:length(propNames)
propInfo = findprop(getImpl(obj), propNames{pi});
if isempty(propInfo) || strcmpi(propInfo.Category, 'none')
category = 'general';
else
category = propInfo.Category;
end
switch category
case 'general'
indices{1}(end+1) = pi;
case 'video'
indices{2}(end+1) = pi;
case 'audio'
indices{3}(end+1) = pi;
end
end
end
end
end