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doc/encoders: Document mediacodec wrapper

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Reviewed-by: Marth64 <marth64@proxyid.net>
Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
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Zhao Zhili
2025-06-13 19:43:38 +08:00
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@ -3342,6 +3342,75 @@ fastest.
@end table
@section MediaCodec
MediaCodec encoder wrapper enables hardware-accelerated video encoding on
Android device. It supports H.264, H.265 (HEVC), VP8, VP9, MPEG-4, and AV1
encoding (whether works or not is device dependent).
Android provides two sets of APIs: Java MediaCodec and NDK MediaCodec. The
MediaCodec encoder wrapper supports both. Note that the NDK MediaCodec API
operates without requiring JVM, but may fail to function outside the JVM
environment due to dependencies on system framework services, particularly
after Android 15.
@table @option
@item ndk_codec @var{boolean}
Use the NDK-based MediaCodec API instead of the Java API. Enabled by default
if @code{av_jni_get_java_vm()} return NULL.
@item ndk_async @var{boolean}
Use NDK MediaCodec in async mode. Async mode has less overhead than poll in a
loop in sync mode. The drawback of async mode is AV_CODEC_FLAG_GLOBAL_HEADER
doesn't work (use extract_extradata bsf when necessary). It doesn't work and
will be disabled automatically on devices below Android 8.0.
@item codec_name @var{string}
A codec type can have multiple implementations on a single device, this option
specify which backend to use (via MediaCodec createCodecByName API). It's NULL
by default, and encoder is created by createEncoderByType.
@item bitrate_mode @var{integer}
Possible values:
@table @samp
@item cq
Constant quality mode
@item vbr
Variable bitrate mode
@item cbr
Constant bitrate mode
@item cbr_fd
Constant bitrate mode with frame drops
@end table
@item pts_as_dts @var{boolean}
Use PTS as DTS. This is a workaround since MediaCodec API doesn't provide
decoding timestamp. It is enabled automatically if B frame is 0.
@item operating_rate @var{integer}
The desired operating rate that the codec will need to operate at, zero for
unspecified. This is used for cases like high-speed/slow-motion video capture,
where the video encoder format contains the target playback rate (e.g. 30fps),
but the component must be able to handle the high operating capture rate (e.g.
240fps). This rate will be used by codec for resource planning and setting the
operating points.
@item qp_i_min @var{integer}
Minimum quantization parameter for I frame.
@item qp_p_min @var{integer}
Minimum quantization parameter for P frame.
@item qp_b_min @var{integer}
Minimum quantization parameter for B frame.
@item qp_i_max @var{integer}
Maximum quantization parameter for I frame.
@item qp_p_max @var{integer}
Maximum quantization parameter for P frame.
@item qp_b_max @var{integer}
Maximum quantization parameter for B frame.
@end table
@section MediaFoundation
This provides wrappers to encoders (both audio and video) in the