On Sun, 2022-11-20 at 14:49 +0800, Zhao Zhili wrote: > From: Zhao Zhili <zhiliz...@tencent.com> > > > v2: > > Rebased on master. > > 01/12: Use crop-width/crop-height as fallback and add TODO. Co- > authored-by: Aman Karmani > 07/12: Fix libavcodec/version.h conflict > 10/12: Change default i-frame-interval to 1 and add log message; bump > minor version > 12/12: Fix rebase conflict > > > v1: > Firstly, some bugs were fixed (patch 1-4). > > Patch 5 and 6 make mediacodec_wrapper support Java MediaCodec and NDK > MediaCodec. The use case I'm considering is run FFmpeg on cmdline > without JVM, > for example, run FFmpeg inside of termux (an Android terminal > emulator). It's > well known that NDK MediaCodec missing some important functions, like > get the > list of codecs, but still useable. > > Patch 7 add NDK MediaCodec decoder support. It can be enabled via > options, > and enabled automatically if no JVM is available. > > Patch 8 add ANativeWindow support to hwcontext_mediacodec. It can be > set by > user, and can be created via AMediaCodec_createPersistentInputSurface > automatically. This is a preparation for encoder. > > Patch 9 makes MediaCodec decoder to support ANativeWindow directly. > It worth > to note that AVMediaCodecContext has only surface. Although we > provided > av_mediacodec_alloc_context(), we didn't strictly prevent users to > allocate > AVMediaCodecContext on stack. I'm not sure if it's OK to add new > field to > AVMediaCodecContext. > > Patch 10 add MediaCodec encoder support. Frame can be feed to encoder > via > buffer, or via Surface/ANativeWindow. If Surface/ANativeWindow is > used, and > the frames come from our MediaCodec decoder wrapper, we can control > it's > 'render' (send to encoder's surface) via > av_mediacodec_release_buffer(). A DTS > generation strategy works in this case. However, if frames comes from > other > sources, like a camera, there is no way to control the 'render' yet, > so DTS is > missing in this case. > > Finally, we can do mediacodec transcoding with FFmpeg cmdline on > Android. > More importantly, we can do MediaCodec decoder to encoder without > copy frames, > although it's very limited since most of avfilters doesn't work. For > example: > > ./ffmpeg -hwaccel mediacodec -hwaccel_output_format mediacodec -i > /sdcard/test.mp4 -an -c:v h264_mediacodec -y /sdcard/out.mp4 > > Since there is no real AVHWFrameContext implementation in > hwcontext_mediacodec. > there is no hwframe_ctx for mediacodec and av_hwframe_transfer_data() > doesn't > work. So if -hwaccel_output_format isn't being specified like: > > ./ffmpeg -hwaccel mediacodec -i /sdcard/test.mp4 -an -c:v > h264_mediacodec -y /sdcard/out.mp4 > > It will trigger a crash in av_hwframe_transfer_data. Patch 11 add a > check on > hwframe_ctx. Patch 12 set hwaccel_output_format automatically to > avoid such > case. >
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