| ffmpeg | 53 |Lua bindings to FFmpeg libraries. | 54 |
| ffmpeg.torch | 57 |Torch utilities for Lua bindings to FFmpeg libraries. | 58 |
| README.md | 64 |65 | |
| LICENSE | 68 |69 | |
ffmpegLua bindings to FFmpeg libraries.
58 |59 | 60 |
61 || new (path) | 73 |Opens a video file for reading. | 74 |
| Video:filter (pixel_format_name[, filterchain='null']) | 80 |Sets a filter to apply to the video. | 81 |
| Video:duration () | 84 |Gets the video duration in seconds. | 85 |
| Video:pixel_format_name () | 88 |Gets the name of the video pixel format. | 89 |
| Video:read_video_frame () | 92 |Reads the next video frame. | 93 |
| VideoFrame:to_ascii () | 99 |Converts the video frame to an ASCII visualisation. | 100 |
184 | -- Set up a filter which scales the video to 128x128 pixels, flips it 185 | -- horizontally and sets the output pixel format to 24-bit RGB: 186 | video = video:filter('rgb24', 'scale=128x128,hflip')187 | 188 | 189 |
ffmpeg.torchTorch utilities for Lua bindings to FFmpeg libraries.
56 |The Torch module must 57 | be installed for ffmpeg.torch to work.
58 || VideoFrame:to_byte_tensor () | 70 |Converts the video frame to a Torch tensor. | 71 |
monadMonad stuffs.
54 |Some code is based on 55 | Douglas Crockford's JavaScript monads.
56 |monad.resultA theoretical union type for Value and Error.
60 | For example, if a function is documented as returning a string Result,
61 | this means that it returns a Value wrapping a string on success, or an
62 | Error otherwise.
Here's an example of using a function that returns a Result:
68 | some_function():and_then(function(value) 69 | print('some_function returned ' .. value) 70 | end):catch(function(error_message)) 71 | print('Error calling some_function: ' .. error_message) 72 | end) 73 |74 | 75 |
However, the real beauty of this approach comes with chaining calls:
76 | 77 | 78 |79 | create_a_shape() 80 | :scale(2) 81 | :rotate(45) 82 | :translate(10, 5) 83 | :catch(function(error_message)) 84 | print('Error creating and transforming shape: ' .. error_message) 85 | end) 86 |87 | 88 |
In the above example we assume that createashape() returns a Result.
89 | If any of the steps along the way fails, no further methods will be called
90 | and the catch function will be triggered. If all of the steps are successful,
91 | the catch function will not be called.
At some point you may want to unwrap a Value to get the actual value inside 94 | of it. A good pattern for doing this is as follows:
95 | 96 | 97 |98 | local my_shape = create_a_shape() 99 | :scale(2) 100 | :rotate(45) 101 | :translate(10, 5) 102 | :catch(function(error_message)) 103 | return default_shape 104 | end) 105 | :get() 106 |107 | 108 |
:get is a special function which returns the value wrapped by a Value.
109 | But be careful! If you call get on an Error then a Lua error will be
110 | raised - this is why in the example above we make sure that we make a
111 | default value available in the case of an Error.
| Error () | 124 |Returns a factory for making Error monads. | 125 |
| Value () | 128 |Returns a factory for making Value monads. | 129 |
| m:done (...) | 135 |Alias for Error:get |
136 |
| m:get () | 139 |Rethrows the error. | 140 |
| m:catch (callback) | 143 |Calls function callback with the error message. |
144 |
| m:and_then (callback) | 147 |Returns self (callback is not called). |
148 |
| m:done (...) | 154 |Alias for Value:get |
155 |
| m:get () | 158 |Returns the wrapped value. | 159 |
| m:catch (callback) | 162 |Returns self (callback is not called). |
163 |
| m:and_then (callback) | 166 |Calls function callback with the wrapped value. |
167 |
192 | local error_factory = monad.Error() 193 | local error_monad = error_factory('An error occurred!')194 | 195 | 196 |
212 | local value_factory = monad.Value() 213 | local value_monad = value_factory(42)214 | 215 | 216 |
A monad which represents an error result.
223 | 224 |An ErrorMonad will:
225 | 226 |:get or :done is called on it.callback with the error message when :catch(callback)
229 | is called on it.Error:get
241 |
242 |
243 | callback with the error message.
285 |
286 |
287 | callback.
302 | callback is not called).
314 |
315 |
316 | A monad which represents a successful result value.
343 | 344 |A Value monad will:
345 | 346 |:get or :done is called on it.callback with the wrapped value when
349 | :and_then(callback) is called on it.:catch().Result.Value:get
364 |
365 |
366 | callback is not called).
408 |
409 |
410 | callback with the wrapped value.
437 |
438 |
439 | callback.
454 | resultA theoretical union type for Value and Error.
60 | For example, if a function is documented as returning a string Result,
61 | this means that it returns a Value wrapping a string on success, or an
62 | Error otherwise.
Here's an example of using a function that returns a Result:
68 | some_function():and_then(function(value) 69 | print('some_function returned ' .. value) 70 | end):catch(function(error_message)) 71 | print('Error calling some_function: ' .. error_message) 72 | end) 73 |74 | 75 |
However, the real beauty of this approach comes with chaining calls:
76 | 77 | 78 |79 | create_a_shape() 80 | :scale(2) 81 | :rotate(45) 82 | :translate(10, 5) 83 | :catch(function(error_message)) 84 | print('Error creating and transforming shape: ' .. error_message) 85 | end) 86 |87 | 88 |
In the above example we assume that createashape() returns a Result.
89 | If any of the steps along the way fails, no further methods will be called
90 | and the catch function will be triggered. If all of the steps are successful,
91 | the catch function will not be called.
At some point you may want to unwrap a Value to get the actual value inside 94 | of it. A good pattern for doing this is as follows:
95 | 96 | 97 |98 | local my_shape = create_a_shape() 99 | :scale(2) 100 | :rotate(45) 101 | :translate(10, 5) 102 | :catch(function(error_message)) 103 | return default_shape 104 | end) 105 | :get() 106 |107 | 108 |
:get is a special function which returns the value wrapped by a Value.
109 | But be careful! If you call get on an Error then a Lua error will be
110 | raised - this is why in the example above we make sure that we make a
111 | default value available in the case of an Error.
| Error () | 124 |Returns a factory for making Error monads. | 125 |
| Value () | 128 |Returns a factory for making Value monads. | 129 |
| monad:done (...) | 135 |Alias for Error:get |
136 |
| monad:get () | 139 |Rethrows the error. | 140 |
| monad:catch (callback) | 143 |Calls function callback with the error message. |
144 |
| monad:and_then (callback) | 147 |Returns self (callback is not called). |
148 |
| monad:done (...) | 154 |Alias for Value:get |
155 |
| monad:get () | 158 |Returns the wrapped value. | 159 |
| monad:catch (callback) | 162 |Returns self (callback is not called). |
163 |
| monad:and_then (callback) | 166 |Calls function callback with the wrapped value. |
167 |
Returns a factory for making Error monads.
184 | 185 |local error_factory = monad.Error()
186 | local error_monad = error_factory('An error occurred!')
187 | Returns a factory for making Value monads.
204 | 205 |local value_factory = monad.Value()
206 | local value_monad = value_factory(42)
207 | A monad which represents an error result.
223 | 224 |An Error monad will:
225 | 226 |:get or :done is called on it.callback with the error message when :catch(callback)
229 | is called on it.Error:get
241 |
242 |
243 | callback with the error message.
285 |
286 |
287 | callback.
302 | callback is not called).
314 |
315 |
316 | A monad which represents a successful result value.
343 | 344 |A Value monad will:
345 | 346 |:get or :done is called on it.callback with the wrapped value when
349 | :and_then(callback) is called on it.:catch().Result.Value:get
364 |
365 |
366 | callback is not called).
408 |
409 |
410 | callback with the wrapped value.
437 |
438 |
439 | callback.
454 | Copyright (c) 2015 Aiden Nibali
53 | 54 |Permission is hereby granted, free of charge, to any person obtaining a copy 55 | of this software and associated documentation files (the "Software"), to deal 56 | in the Software without restriction, including without limitation the rights 57 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 58 | copies of the Software, and to permit persons to whom the Software is 59 | furnished to do so, subject to the following conditions:
60 | 61 |The above copyright notice and this permission notice shall be included in all 62 | copies or substantial portions of the Software.
63 | 64 |THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 65 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 66 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 67 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 68 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 69 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 70 | SOFTWARE. 71 | 72 |
LuaJIT FFI bindings to FFmpeg libraries.
58 | 59 | 60 |64 | local ffmpeg = require('ffmpeg') 65 | 66 | ffmpeg.new('./example.mpg') 67 | :filter('gray', 'scale=40:12') 68 | :read_video_frame() 69 | :to_ascii() 70 | :and_then(function(ascii_frame) 71 | print(ascii_frame) 72 | end) 73 | :catch(function(err) 74 | print('An error occurred: ' .. err) 75 | end) 76 |77 | 78 |
If you have Torch installed, load the enhanced version of the library.
81 | 82 | 83 |84 | local ffmpeg = require('ffmpeg.torch') 85 | 86 | local first_frame_tensor = ffmpeg.new('./example.mpg') 87 | :filter('rgb24', 'scale=512:512') 88 | :read_video_frame() 89 | :to_byte_tensor() 90 | :catch(function(err) 91 | -- Use the Lena image in case of error 92 | return image:lena() 93 | end) 94 | :get() 95 |96 | 97 | 98 | 99 |