Newest 'ffmpeg' Questions - Stack Overflow

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  • ffmpeg result to a tempfile

    26 septembre 2012, par user1165201

    I am new to python and ffmpeg. I have a following question to ask.

    If I run the following command from command-line and it works.

    ffmpeg -i  1.flv  temp_filename

    If I put it in a program

       temp_file_handle, temp_filename = tempfile.mkstemp('.flv')

   command = "ffmpeg -i " + newvideo.location + " "+ temp_filename

   out = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
   res = out.communicate()

    The generated video didn't write to the tem_filename. Why?

  • ffmpeg keyframe extraction

    26 septembre 2012, par Shikhar Shrivastav

    I have been trying to extract keyframes from video using ffmpeg 0.11.1 . So far all the commands I have tried do not extract keyframes but return all the frames ie 25fps*total time number of frames in the output. I tried setting the keyint_min as 25 to make sure there is a amximum of 1 keyframe per second.

    ffmpeg -vf select="eq(pict_type\,PICT_TYPE_I)" -g 250 -keyint_min 25 -i C:\test.mp4 -vsync 2 -f image2 C:\testTemp\thumbnails-%02d.jpeg

    But still all the frames are returned.

    Then i tried, to separate the keyframes by 20 seconds.

    ffmpeg -i C:\test.mp4 -vf select='eq(pict_type\,I)*(isnan(prev_selected_t)+gte(t-prev_selected_t\,20))' -vsync 0 -f image2 C:\testTemp\%09d.jpg

    Again same result, all the frames are returned.

    What should I do?

  • Encode image to video using ffmpeg (sws_scale)

    26 septembre 2012, par bahar_p

    I'm trying to encode an image to video using ffmpeg library. I have these global params:

    //Global params
AVCodec         *codec;
AVCodecContext  *codecCtx;
uint8_t         *output_buffer;
int             output_buffer_size;

    I divided the encoding to 3 methods: Initialize the encoder:

    jint Java_com_camera_simpledoublewebcams2_CameraPreview_initencoder(JNIEnv* env,jobject thiz){
avcodec_register_all();
avcodec_init();
av_register_all();

int fps = 30;

/* find the H263 video encoder */
codec = avcodec_find_encoder(CODEC_ID_H263);
if (!codec) {
    LOGI("avcodec_find_encoder() run fail.");
    return -5;
}

//allocate context
codecCtx = avcodec_alloc_context();

/* put sample parameters */
codecCtx->bit_rate = 400000;
/* resolution must be a multiple of two */
codecCtx->width = 176;
codecCtx->height = 144;
/* frames per second */
codecCtx->time_base = (AVRational){1,fps};
codecCtx->pix_fmt = PIX_FMT_YUV420P;
codecCtx->codec_id = CODEC_ID_H263;
codecCtx->codec_type = AVMEDIA_TYPE_VIDEO;

/* open it */
if (avcodec_open(codecCtx, codec) < 0) {
    LOGI("avcodec_open() run fail.");
    return -10;
}

//init buffer
output_buffer_size = 500000;
output_buffer = malloc(output_buffer_size);

return 0;

    }

    Encoding the image:

    jint Java_com_camera_simpledoublewebcams2_CameraPreview_encodejpeg(JNIEnv* env,jobject thiz,jchar* cImage, jint imageSize){
int             out_size;
AVFrame         *picture;
AVFrame         *outpic;
uint8_t         *outbuffer;

//allocate frame    
picture = avcodec_alloc_frame();    
outpic = avcodec_alloc_frame();

int nbytes = avpicture_get_size(PIX_FMT_YUV420P, codecCtx->width, codecCtx->height);
outbuffer = (uint8_t*)av_malloc(nbytes);
outpic->pts = 0;

//fill picture with image
avpicture_fill((AVPicture*)picture, (uint8_t*)cImage, PIX_FMT_RGBA, codecCtx->width, codecCtx->height);
//fill outpic with empty image
avpicture_fill((AVPicture*)outpic, outbuffer, PIX_FMT_YUV420P, codecCtx->width, codecCtx->height);

//rescale the image 
struct SwsContext* fooContext = sws_getContext(codecCtx->width, codecCtx->height, 
                                                       PIX_FMT_RGBA, 
                                                       codecCtx->width, codecCtx->height, 
                                                       PIX_FMT_YUV420P, 
                                                       SWS_FAST_BILINEAR, NULL, NULL, NULL);
sws_scale(fooContext, picture->data, picture->linesize, 0, codecCtx->height, outpic->data, outpic->linesize);   

//encode the image
out_size = avcodec_encode_video(codecCtx, output_buffer, output_buffer_size, outpic);
out_size += avcodec_encode_video(codecCtx, output_buffer, output_buffer_size, outpic);

//release pictures
av_free(outbuffer);
av_free(picture);
av_free(outpic);

return out_size;

    }

    And closing the encoder:

    void Java_com_camera_simpledoublewebcams2_CameraPreview_closeencoder(JNIEnv* env,jobject thiz){
free(output_buffer);
avcodec_close(codecCtx);
av_free(codecCtx);

    }

    When I send the first image, I get a result from the encoder. When I try to send another image the program crashes. I tried calling init once and then the images, then the close - didn't work. I tried calling the init and the close for every image - didn't work.

    Any suggestions?

    Thanks!

    EDIT: After further research I found that the problem is at sws_scale method. Still don't know what is causing this issue...

  • Compiling ffmpeg for use in Android (ndk) for x86 architecture

    26 septembre 2012, par Ankur22

    I am trying to compile ffmpeg for Android but for the x86 architecture. I've successfully compiled an arm .so and it all works, and I though that by replacing arm with x86 in the relevant places within the build script would have done the trick. Unfortunately that's not the case and I get some strange things occurring.

    First I get this while it's compiling ffmpeg:

    /home/ankur/android-ndk-r8/platforms/android-8/arch-arm//usr/include/strings.h:49: warning: redundant redeclaration of 'index'

    Notice the arch-arm instead of arch-x86. Finally I get this:

    /home/ankur/android-ndk-r8/toolchains/x86-4.4.3/prebuilt/linux-x86/bin/i686-android-linux-ld: libavcodec/libavcodec.a(4xm.o): Relocations in generic ELF (EM: 40)
/home/ankur/android-ndk-r8/toolchains/x86-4.4.3/prebuilt/linux-x86/bin/i686-android-linux-ld: libavcodec/libavcodec.a(4xm.o): Relocations in generic ELF (EM: 40)
/home/ankur/android-ndk-r8/toolchains/x86-4.4.3/prebuilt/linux-x86/bin/i686-android-linux-ld: libavcodec/libavcodec.a(4xm.o): Relocations in generic ELF (EM: 40)
libavcodec/libavcodec.a(4xm.o): could not read symbols: File in wrong format

    The build script I've created looks like this:

    #!/bin/bash

NDK=~/android-ndk-r8
PLATFORM=$NDK/platforms/android-8/arch-x86/
PREBUILT=$NDK/toolchains/x86-4.4.3/prebuilt/linux-x86
function build_one_r8
{
./configure \
    --disable-shared \
    --enable-static \
    --enable-gpl \
    --enable-version3 \
    --enable-nonfree \
    --disable-doc \
    --disable-ffmpeg \
    --disable-ffplay \
    --disable-ffprobe \
    --disable-ffserver \
    --disable-avdevice \
    --disable-avfilter \
    --disable-postproc \
    --enable-small \
    --cross-prefix=$PREBUILT/bin/i686-android-linux- \
    --enable-cross-compile \
    --target-os=linux \
    --extra-cflags="-I$PLATFORM/usr/include" \
    --arch=x86 \
    --disable-symver \
    --disable-debug \
    --disable-stripping \
    $ADDITIONAL_CONFIGURE_FLAG
sed -i 's/HAVE_LRINT 0/HAVE_LRINT 1/g' config.h
sed -i 's/HAVE_LRINTF 0/HAVE_LRINTF 1/g' config.h
sed -i 's/HAVE_ROUND 0/HAVE_ROUND 1/g' config.h
sed -i 's/HAVE_ROUNDF 0/HAVE_ROUNDF 1/g' config.h
sed -i 's/HAVE_TRUNC 0/HAVE_TRUNC 1/g' config.h
sed -i 's/HAVE_TRUNCF 0/HAVE_TRUNCF 1/g' config.h
make clean
make  -j4 install
$PREBUILT/bin/i686-android-linux-ar d libavcodec/libavcodec.a inverse.o
$PREBUILT/bin/i686-android-linux-ld -rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib  -soname libffmpeg.so -shared -nostdlib  -z,noexecstack -Bsymbolic --whole-archive --no-undefined -o $PREFIX/libffmpeg.so libavcodec/libavcodec.a libavformat/libavformat.a libavutil/libavutil.a libswscale/libswscale.a -lc -lm -lz -ldl -llog  --warn-once  --dynamic-linker=/system/bin/linker $PREBUILT/lib/gcc/i686-android-linux/4.4.3/libgcc.a
}
function build_one_r8_2
{
$PREBUILT/bin/i686-android-linux-ar d libavcodec/libavcodec.a inverse.o
$PREBUILT/bin/i686-android-linux-ld -rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib  -soname libffmpeg.so -shared -nostdlib  -z,noexecstack -Bsymbolic --whole-archive --no-undefined -o $PREFIX/libffmpeg.so libavcodec/libavcodec.a libavformat/libavformat.a libavutil/libavutil.a libswscale/libswscale.a -lc -lm -lz -ldl -llog  --warn-once  --dynamic-linker=/system/bin/linker $PREBUILT/lib/gcc/i686-android-linux/4.4.3/libgcc.a
}
#x86
CPU=x86
OPTIMIZE_CFLAGS="-march=$CPU "
PREFIX=./android/$CPU
ADDITIONAL_CONFIGURE_FLAG=
build_one_r8

    I hope I'm doing something wrong rather than this not being possible.

    Thanks!

  • Start using ffmpeg Android with NDK - Windows

    26 septembre 2012, par idish

    I'm new to ffmpeg and I'm trying to compile it/use it's libraries in my Android App with Android NDK. I have everything ready: the NDK, the ffmpeg source, but I've been searching the web for long time trying to compile some ffmpeg into my app. I found this answer, but I don't really understand the instructions, I repeat, I'm using Windows, not a Linux based operating system. Is it that hard to make ffmpeg work in my android app? Could anyone please give me instructions to get it work?

    Thank you.

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