ffmpeg, Debugging Android FFmpeg (1)

<span id="Label3"></p><p><p>Target issues</p></p> <ol> <ol> <li><p>For JPEG encoding why not use LIBJPEG instead of MPEG (right is this movie antique Format) code?</p><p>Actually found even WMV and so on some usually do not need to break things, are and MPEG antique common use a set of Code. Does JPEG have anything to do with mpeg? Overhead Not much?</p></li> <li><p>Why is MJPEG (that is, continuous JPEG) encoded output, when encoding the n+1 sub-graph to really output the JPEG encoding results of the nth image?</p></li> <li><p>Each get a copy of the original input data, then the memory seems to be copied to new memory, and then discarded, huge picture of the time, this copy is a waste of cpu, how to let him not copy but directly with Raw memory. anyway, a picture is not anxious, why copy it.</p></li> </ol> </ol><p><p><br></p></p><p><p>first, a ffmpeg command line for android, to debug version, The key is configure when added</p></p><pre><pre>--enable-debug--disable-stripping</pre></pre><p><p>For example:</p></p><p><p>Prepare a standard GCC tool chain from the NDK for subsequent cross-platform Compilation.</p></p><pre>echo ---------------make standard gcc tool chain from android  NDK--------------------ls -d ./std_toolchain && { echo ./std_toolchain  already exist; exit 0; }printenv android_ndk_root > /dev/null  | |  { echo please export android_ndk_root=root_dir_of_your_android_ndk; exit 1 ;  }platform=$ (basename $ (ls -d  $ANDROID _ndk_root/platforms/android-8));  test -z   $PLATFORM  && exit 1toolchain=$ (basename $ (ls -d  $ANDROID _ndk_root/ toolchains/arm-linux-androideabi-[4-5].* | tail -n 1)); test -z  $TOOLCHAIN  && exit 1work_system=$ (basename $ (ls -d  $ANDROID _ndk_root/toolchains/ arm-linux-androideabi-[4-5].*/prebuilt/* | tail -n 1)); test -z  $WORK _ System &&&nbsP;exit 1$android_ndk_root/build/tools/make-standalone-toolchain.sh --install-dir=./std_toolchain  --platform= $PLATFORM  --toolchain= $TOOLCHAIN  --system= $WORK _system --arch=arm -- verboseecho  ""; echo ok; echo  "" export path= "$PWD/std_toolchain/bin: $PATH" Export  cc=arm-linux-androideabi-gcc</pre><p><p>And then go to Ffmpeg's Source to execute the Configure.</p></p><pre><pre>./configure--enable-cross-compile--cross-prefix=arm-linux-androideabi---target-os=linux--arch=armv7--cpu= Armv7-a--disable-doc--disable-ffplay--disable-ffprobe--disable-ffserver--disable-symver--enable-debug--disable -stripping--disable-everything--enable-static--enable-protocol=pipe--enable-filter=scale--enable-filter=cro P--enable-filter=transpose--enable-demuxer=rawvideo--enable-decoder=rawvideo--enable-muxer=image2--enable-muxe R=image2pipe--enable-muxer=mjpeg--enable-encoder=mjpeg</pre></pre><p><p>Just an example, leaving only support for the Rawvideo input format and the MJPEG output format.</p></p><p><p>Then make, get Ffmpeg.</p></p><p><p>Uploaded to Android/data/local/tmp/.</p></p><p><p><span style="line-height: 22.5px;">(some More specific preparatory steps refer to</span> Android native debug: manual use of gdbserver Remote Debug C code <span style="line-height: 22.5px;">)</span></p></p><p><p>then, Start gdbserver,</p></p><p><p>Cond.<br></p></p><p><p><br></p></p><p><p>ffmpeg, Debugging Android FFmpeg (1)</p></p></span>