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--- doc:appunti:android:logo_bootanimation [2019/10/07 10:41] – [log.bin] niccolo
+++ doc:appunti:android:logo_bootanimation [2019/10/07 16:32] – [Contents of bootanimation.zip] niccolo
@@ Line 11: / Line 11: @@
 The boot logo is contained into a dedicated partition called **logo**, you can find the binary image called **logo.bin** packed into the stock ROM archive or you can download it from the phone using the **SP Flash Tool** program.
-The partition image contains **several different pictures** (39 in our case!), some are at full screen size (720x1280 pixels), others are snippets used to represent e.g. the charging battery, the percentage, etc. The **logo.bin** has a rather simple structure:
+The partition image contains **several different pictures** (39 in our case!), some are at full screen size (720x1280 pixels), others are snippets used (before the actual boot stage) to represent e.g. the charging battery, the percentage, etc. The **logo.bin** has a rather simple structure:
 ^  Content             ^  Size (bytes)  ^  Notes  ^
@@ Line 17: / Line 17: @@
 ^ Pictures Count       |              4 | A [[wp>Little-endian|little-endian]] 32bit integer. This is the number of pictures packed into the data block.  |
 ^ Total Block Size     |              4 | A little-endian 32bit integer. This is the total size of the data, excluding only the 512 bytes of the MTK header.  |
-^ Offsets Map          |      4 x Count | For each picture there is a little-endian 32bit integer, indicating the offset of the picture into the data, excluding the 512 bytes header. The first offset is 4 + 4 + (4 * pictures count).  |
+^ Offsets Map          |      4 x Count | For each picture there is a little-endian 32bit integer, indicating the offset of the picture into the data, after the 512 bytes header. The first offset is 4 + 4 + (4 * pictures count).  |
 ^ Pictures Data Block  |       Variable | Each picture is in **raw RGB** format, it is appended as a **z-compressed** file.  |
-FIXME How to extract pictures, how to convert to PNG.
 Here there are two full screen examples:
@@ Line 31: / Line 29: @@
 {{img-24.png?80}}
-===== Web References =====
+==== Unpack and repack the log.bin ====
+Unfortunately the [[https://github.com/rom1nux/mtkimg|mtkimg]] did not work with my logo.bin. The [[https://github.com/rom1nux/mtkimg/issues/6|issue]] is about unsopported signature and RGB format. So I write a Python script, download it here: **{{mtk-android-logo.txt|mtk-android-logo}}**.
+<code>
+./mtk-android-logo unpack
+</code>
+Run the script into the same directory containing the **logo.bin** file; a **logo.d** directory will be created with compressed (.z) and uncompressed (.bin) files.
+<code>
+./mtk-android-logo repack
+</code>
+For repacking, the script needs the original **logo.bin** and a **logo.d** directory containing the pictures. If the z-compressed picture exists, it will be used, otherwise the .bin one is used after z-compressing it. The resulting image is saved as **logo.repack.bin**.
+Pictures are expected to be **raw RGB**, stored with **z-compression**. The pixel size (width x height) of each picture must be guessed.
+Suppose that th e screen size is 720x1280 and the biggest, uncompressed picture is 3686400 bytes:
+<code>
+3686400 / (720 * 1280) = 4
+</code>
+so we can desume that the picture is 4 bytes/pixel, i.e. a 32bit RGB. By **trial and error** we found that it is an BGRA (Blue, Green, Red and Alpha), we can convert it into PNG with **ffmpeg**, specifying the **bgra** pixel format:
+<code>
+ffmpeg -vcodec rawvideo -f rawvideo \
+    -pix_fmt bgra -s 720x1280 -i "img-01.bin" \
+    -f image2 -vcodec png "img-01.png"
+</code>
+Once edited, we can convert it back to raw BGRA with:
+<code>
+ffmpeg -vcodec png -i "img-01.png" \
+    -vcodec rawvideo -f rawvideo -pix_fmt bgra "img-01.bin"
+</code>
+It is known that also 16bit raw formats are used (eg. bgr565le), you can guess it, if the size of the picture is 2 bytes per pixel. You can list all the pixel formats supprted by ffmpeg by running:
+<code>
+  ffmpeg -pix_fmts
+</code>
+===== bootanimation.zip =====
+The logo contained into the **logo.bin** partition is displayed in the early stage of the boot process. Once the system partition is available, an animation is played for some seconds. That animation is contained into a zip file. In our case it turned out that the file is stored in **/system/media/bootanimation.zip**. To replace it, being into the **/system/** directory, **root privileges** are required.
+There should be an executable responsible to actually run the animation, it should be **/system/bin/bootanimation**. It may search the bootanimation.zip in several directories, where the first one found, will be used. Searched directories can be:
+  * **/custom/media/bootanimation.zip**
+  * **/oem/media/bootanimation.zip**
+  * **/data/local/bootanimation.zip**
+  * **/system/media/bootanimation.zip**
+If bootanimation.zip file is **not found**, the **framework-res.apk** package is searched into directories **/system/customer/framework/** or **/system/framework/**, that file contains two images that are used as a fall-back animation:
+  * assets/images/android-logo-mask.png
+  * assets/images/android-logo-shine.png
+==== Contents of bootanimation.zip ====
+Generally the animation is composed of **two parts**: the first is played just **once**, the second part is played in **loop** until the system is ready. This is controlled by the contents of the **desc.txt** file contained into the zip, here it is an example:
+<file>
+1280 15
+p 1 0 part0
+p 0 0 part1
+</file>
+The first line tell us that the animation is **720x1280 pixels**, at **15 frames per second**.
+The second line tell us that there is a part of **type p** to be executed **1** time. The following number (**0** in the example above) someone says that it is a pause to wait after the animation, in my case it is instead ununsed at all. The actual frames are contained into the **part0** subdirectory.
+The last line defines another part **type p** to be executed in an endless (**0**) loop until the system is ready, with a zero **0** pause. The frames are into the **part1** subdirectory.
+A **type p** means that the animation can be interrupted when the boot process is completed. If you want instead a part to be played as the final part of the animation (e.g. if you want a fade-out effect), you have to use a **tpye c**.
+<file>
+1280 15
+p 1 0 part0
+c 0 0 part1
+c 0 0 part2
+</file>
+In the above example, once the boot process is completed, the **part1** is interrupted, and the **part2** is executed. Animation part **type c** was introduced with **Android Jelly Bean** (i.e. Android 4.1 to 4.3.1).
+Frames are actually **PNG images**, of the proper size (720x1280 in our case).
+So the directories structure should be something like this:
+<code>
+.
+├── desc.txt
+├── part0
+│   ├── img_000.png
+│   ├── ...
+│   └── img_196.png
+└── part1
+    ├── img_197.png
+    ├── ...
+    └── img_207.png
+</code>
+To pack eveything into a zip file you can use the command:
+<code>
+zip -r -Z store bootanimation.zip desc.txt part0 part1
+</code>
+Beware of the **%%-Z store%%** option: the zip archive must be created using the **store compression method**, not the //deflate// one.
+===== Web References =====
+  * **[[https://github.com/rom1nux/mtkimg|mtkimg]]** Unpack/Repack boot.img, recovery.img and logo.bin for Mediatek
   * **[[https://forum.xda-developers.com/showthread.php?t=1560836|BOOT ANIMATION explained]]**
+  * **[[http://muzso.hu/2012/07/15/understanding-boot-animations-in-android|Understanding boot animations in Android]]**