fa30c86323
- Allow a duration of 0 - Rename LOOP chunk to ANIM and add the background color field to it. - Add a disposal method field for each animation frame. - Modify webpmux.c binary interface to allow the input of background color and disposal methods. Also make '-loop' and '-bgcolor' arguments optional with some default values. Change-Id: I807372a61cdb8a0d3080ae3552caf2848070bf4d
140 lines
4.5 KiB
Plaintext
140 lines
4.5 KiB
Plaintext
__ __ ____ ____ ____ __ __ _ __ __
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/ \\/ \/ _ \/ _ \/ _ \/ \ \/ \___/_ / _\
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\ / __/ _ \ __/ / / (_/ /__
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\__\__/\_____/_____/__/ \__//_/\_____/__/___/
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Description:
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============
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WebP Mux: library to create a WebP container object for features like
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color profile, metadata, animation and fragmented images. A reference command
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line tool 'webpmux' and WebP container specification
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'doc/webp-container-spec.txt' are also provided in this package.
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WebP Mux tool:
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==============
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The examples/ directory contains a tool (webpmux) for manipulating WebP
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files. The webpmux tool can be used to create a WebP container file and to
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extract or strip relevant data from the container file.
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A list of options is available using the -help command line flag:
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> webpmux -help
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Usage: webpmux -get GET_OPTIONS INPUT -o OUTPUT
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webpmux -set SET_OPTIONS INPUT -o OUTPUT
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webpmux -strip STRIP_OPTIONS INPUT -o OUTPUT
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webpmux -frgm FRAGMENT_OPTIONS [-frgm...] -o OUTPUT
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webpmux -frame FRAME_OPTIONS [-frame...] [-loop LOOP_COUNT]
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[-bgcolor BACKGROUND_COLOR] -o OUTPUT
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webpmux -info INPUT
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webpmux [-h|-help]
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GET_OPTIONS:
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Extract relevant data.
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icc Get ICC profile.
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exif Get EXIF metadata.
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xmp Get XMP metadata.
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frgm n Get nth fragment.
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frame n Get nth frame.
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SET_OPTIONS:
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Set color profile/metadata.
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icc file.icc Set ICC profile.
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exif file.exif Set EXIF metadata.
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xmp file.xmp Set XMP metadata.
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where: 'file.icc' contains the ICC profile to be set,
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'file.exif' contains the EXIF metadata to be set and
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'file.xmp' contains the XMP metadata to be set
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STRIP_OPTIONS:
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Strip color profile/metadata.
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icc Strip ICC profile.
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exif Strip EXIF metadata.
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xmp Strip XMP metadata.
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FRAGMENT_OPTIONS(i):
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Create fragmented image.
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file_i +xi+yi
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where: 'file_i' is the i'th fragment (WebP format),
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'xi','yi' specify the image offset for this fragment.
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FRAME_OPTIONS(i):
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Create animation.
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file_i +xi+yi+di+mi
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where: 'file_i' is the i'th animation frame (WebP format),
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'xi','yi' specify the image offset for this frame.
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'di' is the pause duration before next frame.
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'mi' is the dispose method for this frame (0 or 1).
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LOOP_COUNT:
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Number of times to repeat the animation.
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Valid range is 0 to 65535 [Default: 0 (infinite)].
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BACKGROUND_COLOR:
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Background color of the canvas.
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A,R,G,B
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where: 'A', 'R', 'G' and 'B' are integers in the range 0 to 255 specifying
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the Alpha, Red, Green and Blue component values respectively
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[Default: 255,255,255,255].
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INPUT & OUTPUT are in WebP format.
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Note: The nature of EXIF, XMP and ICC data is not checked and is assumed to be
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valid.
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WebP Mux API:
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==============
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The WebP Mux API contains methods for adding data to and reading data from
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WebPMux (a WebP container object). This API currently supports XMP/EXIF
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metadata, ICC profile, animation and fragmented images. Other features
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will be added in subsequent releases.
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Example#1 (pseudo code): Creating a WebPMux object with image data, color
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profile and XMP metadata.
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int copy_data = 0;
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WebPMux* mux = WebPMuxNew();
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// ... (Prepare image data).
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WebPMuxSetImage(mux, &image, copy_data);
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// ... (Prepare ICC profile data).
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WebPMuxSetChunk(mux, "ICCP", &icc_profile, copy_data);
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// ... (Prepare XMP metadata).
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WebPMuxSetChunk(mux, "XMP ", &xmp, copy_data);
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// Get data from mux in WebP RIFF format.
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WebPMuxAssemble(mux, &output_data);
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WebPMuxDelete(mux);
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// ... (Consume output_data; e.g. write output_data.bytes to file).
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WebPDataClear(&output_data);
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Example#2 (pseudo code): Get image and color profile data from a WebP file.
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int copy_data = 0;
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// ... (Read data from file).
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WebPMux* mux = WebPMuxCreate(&data, copy_data);
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WebPMuxGetFrame(mux, 1, &image);
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// ... (Consume image; e.g. call WebPDecode() to decode the data).
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WebPMuxGetChunk(mux, "ICCP", &icc_profile);
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// ... (Consume icc_profile).
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WebPMuxDelete(mux);
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free(data);
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For detailed Mux API reference, please refer to the header file (src/webp/mux.h)
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Bugs:
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=====
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Please report all bugs to our issue tracker:
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http://code.google.com/p/webp/issues
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Patches welcome! See this page to get started:
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http://www.webmproject.org/code/contribute/submitting-patches/
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Discuss:
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========
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Email: webp-discuss@webmproject.org
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Web: http://groups.google.com/a/webmproject.org/group/webp-discuss
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