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Merge "media: document rotation and scaling issues for MediaCodec" into nyc-dev

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This commit is contained in:
Lajos Molnar
2016-06-28 22:21:01 +00:00
committed by Android (Google) Code Review
parent 556e012979 4461356ea8
commit af9d9f9b3e
2 changed files with 43 additions and 4 deletions
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43
media/java/android/media/MediaCodec.java
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@@ -606,6 +606,32 @@ import java.util.Map;
Also since {@link android.os.Build.VERSION_CODES#M}, you can change the output Surface
dynamically using {@link #setOutputSurface setOutputSurface}.
<h4>Transformations When Rendering onto Surface</h4>
If the codec is configured into Surface mode, any crop rectangle, {@linkplain
MediaFormat#KEY_ROTATION rotation} and {@linkplain #setVideoScalingMode video scaling
mode} will be automatically applied with one exception:
<p class=note>
Prior to the {@link android.os.Build.VERSION_CODES#M} release, software decoders may not
have applied the rotation when being rendered onto a Surface. Unfortunately, there is no way to
identify software decoders, or if they apply the rotation other than by trying it out.
<p>
There are also some caveats.
<p class=note>
Note that the pixel aspect ratio is not considered when displaying the output onto the
Surface. This means that if you are using {@link #VIDEO_SCALING_MODE_SCALE_TO_FIT} mode, you
must position the output Surface so that it has the proper final display aspect ratio. Conversely,
you can only use {@link #VIDEO_SCALING_MODE_SCALE_TO_FIT_WITH_CROPPING} mode for content with
square pixels (pixel aspect ratio or 1:1).
<p class=note>
Note also that as of {@link android.os.Build.VERSION_CODES#N} release, {@link
#VIDEO_SCALING_MODE_SCALE_TO_FIT_WITH_CROPPING} mode may not work correctly for videos rotated
by 90 or 270 degrees.
<p class=note>
When setting the video scaling mode, note that it must be reset after each time the output
buffers change. Since the {@link #INFO_OUTPUT_BUFFERS_CHANGED} event is deprecated, you can
do this after each time the output format changes.
<h4>Using an Input Surface</h4>
<p>
When using an input Surface, there are no accessible input buffers, as buffers are automatically
@@ -3055,7 +3081,13 @@ final public class MediaCodec {
/**
* The content is scaled, maintaining its aspect ratio, the whole
* surface area is used, content may be cropped
* surface area is used, content may be cropped.
* <p class=note>
* This mode is only suitable for content with 1:1 pixel aspect ratio as you cannot
* configure the pixel aspect ratio for a {@link Surface}.
* <p class=note>
* As of {@link android.os.Build.VERSION_CODES#N} release, this mode may not work if
* the video is {@linkplain MediaFormat#KEY_ROTATION rotated} by 90 or 270 degrees.
*/
public static final int VIDEO_SCALING_MODE_SCALE_TO_FIT_WITH_CROPPING = 2;
@@ -3070,10 +3102,15 @@ final public class MediaCodec {
/**
* If a surface has been specified in a previous call to {@link #configure}
* specifies the scaling mode to use. The default is "scale to fit".
* <p class=note>The scaling mode may be reset to the <strong>default</strong> each time an
* <p class=note>
* The scaling mode may be reset to the <strong>default</strong> each time an
* {@link #INFO_OUTPUT_BUFFERS_CHANGED} event is received from the codec; therefore, the client
* must call this method after every buffer change event (and before the first output buffer is
* released for rendering) to ensure consistent scaling mode.</p>
* released for rendering) to ensure consistent scaling mode.
* <p class=note>
* Since the {@link #INFO_OUTPUT_BUFFERS_CHANGED} event is deprecated, this can also be done
* after each {@link #INFO_OUTPUT_FORMAT_CHANGED} event.
*
* @throws IllegalArgumentException if mode is not recognized.
* @throws IllegalStateException if in the Released state.
*/

4
media/java/android/media/MediaFormat.java
View File

@@ -554,7 +554,9 @@ public final class MediaFormat {
/**
* A key describing the desired clockwise rotation on an output surface.
* This key is only used when the codec is configured using an output surface.
* The associated value is an integer, representing degrees.
* The associated value is an integer, representing degrees. Supported values
* are 0, 90, 180 or 270. This is an optional field; if not specified, rotation
* defaults to 0.
*
* @see MediaCodecInfo.CodecCapabilities#profileLevels
*/