MediaFormat浅析

类结构

java.lang.Object

↳ android.media.MediaFormat

类说明

Encapsulates the information describing the format of media data, be it audio or video.

它是音视频数据格式的简单描述

The format of the media data is specified as string/value pairs.

这个格式有点特殊，是string/value键值对

Keys common to all audio/video formats, all keys not marked optional are mandatory:

键一般是音频/视频这样的格式，所有键都是必须的

关键属性和方法说明

/**

* A key describing the bitrate in bits/sec.

* The associated value is an integer

*/

public static finalString KEY_BIT_RATE= "bitrate";

/**

* A key describing the frame rate of a video format in frames/sec.

* The associated value is an integer or a float.

*/

public static finalString KEY_FRAME_RATE= "frame-rate";

/**

* A key describing the color format of the content in a video format.

* Constants are declared in {@linkandroid.media.MediaCodecInfo.CodecCapabilities}.

*/

public static finalString KEY_COLOR_FORMAT= "color-format";

/**

* A key describing the frequency of I frames expressed in secs

* between I frames.

* The associated value is an integer.

*/

public static finalString KEY_I_FRAME_INTERVAL= "i-frame-interval";

/**

* A key describing the number of channels in an audio format.

* The associated value is an integer

*/

public static finalString KEY_CHANNEL_COUNT= "channel-count";

/**

* A key describing the capture rate of a video format in frames/sec.

*<p>

* When capture rate is different than the frame rate, it means that the

* video is acquired at a different rate than the playback, which produces

* slow motion or timelapse effect during playback. Application can use the

* value of this key to tell the relative speed ratio between capture and

* playback rates when the video was recorded.

*</p>

*<p>

* The associated value is an integer or a float.

*</p>

*/

public static finalString KEY_CAPTURE_RATE= "capture-rate";

/**

* Applies only when configuring a video encoder in "surface-input" mode.

* The associated value is a long and gives the time in microseconds

* after which the frame previously submitted to the encoder will be

* repeated (once) if no new frame became available since.

*/

public static finalString KEY_REPEAT_PREVIOUS_FRAME_AFTER

="repeat-previous-frame-after";

使用实例

MediaFormat mediaFormat = MediaFormat.createVideoFormat("video/avc",windowWidth,windowHeight);

mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE,1200000);

mediaFormat.setInteger(MediaFormat.KEY_FRAME_RATE,25);

mediaFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface);

mediaFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL,1);

mediaFormat.setInteger(MediaFormat.KEY_CHANNEL_COUNT,1);

mediaFormat.setInteger(MediaFormat.KEY_CAPTURE_RATE,25);

mediaFormat.setInteger(MediaFormat.KEY_REPEAT_PREVIOUS_FRAME_AFTER,1000000/ 25);