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• libav sws_scale() fails colorspace conversion on real device, works on emulator

  26 août 2020, par chugadie

  I'm making a movie player with libav. I have decoding video packets working, I have play in reverse working, I have seeking working. All this works no an x86 android emulator, but fails to work on a real android phone (arm64-v8a)

  


  The failure is in sws_scale() - it returns 0. The video frames continue to be decoded properly with no errors.

  


  There are no errors, warnings, alerts from libav. I have connected an avlog_callback

  


  void log_callback(void *ptr, int level, const char *fmt, va_list vargs) {
    if (level<= AV_LOG_WARNING)
        __android_log_print( level, LOG_TAG, fmt, vargs);
}
uint64_t openMovie( char* path, int rotate, float javaDuration )
{
    av_log_set_level(AV_LOG_WARNING);
    av_log_set_callback(log_callback);


  


  The code to do the sws_scale() is :

  


  int JVM_getBitmapBuffer( JNIEnv* env, jobject thiz, jlong av, jobject bufferAsInt, jbyte transparent ) { 
    avblock *block = (avblock *) av;
    if (!block) {
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  avblock is null");
        return AVERROR(EINVAL);
    }
    if (!block->pCodecCtx) {
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  codecctx is null");
        return AVERROR(EINVAL);
    }

    int width = block->pCodecCtx->width;
    int height = block->pCodecCtx->height;

    if (NULL == block->sws) {
        __android_log_print( ANDROID_LOG_ERROR, LOG_TAG, "getBitmapBuffer:\n  *** invalid sws context ***" );
    }

    int scaleRet = sws_scale( block->sws,
            block->pFrame->data,
            block->pFrame->linesize,
            0,
            height,
            block->pFrameRGB->data,
            block->pFrameRGB->linesize
    );
    if (scaleRet == 0 ) {
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  scale failed");
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  pframe linesize    %d", block->pFrame->linesize[0]); 
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  pframergb linesize %d", block->pFrameRGB->linesize[0]); 
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  height  %d",
        height);
        return AVERROR(EINVAL);
    }


  


  Setting up the codex and avframes :

  


  //i have tried every combination of 1, 8, 16, and 32 for these values
int alignRGB = 32;
int align    = 16; 
int width    = block->pCodecCtx->width;
int height   = block->pCodecCtx->height;
block->pFrame    = av_frame_alloc();
block->pFrameRGB = av_frame_alloc();

block->pFrameRGBBuffer = av_malloc(
    (size_t)av_image_get_buffer_size(AV_PIX_FMT_RGB32, width, height, alignRGB) 
);

av_image_fill_arrays(
    block->pFrameRGB->data,
    block->pFrameRGB->linesize,
    block->pFrameRGBBuffer,
    AV_PIX_FMT_RGB32,
    width,
    height,
    alignRGB
);

block->pFrameBuffer = av_malloc(
        (size_t) av_image_get_buffer_size(block->pCodecCtx->pix_fmt,
                                          width, height, align
        )
);
av_image_fill_arrays(
    block->pFrame->data,
    block->pFrame->linesize,
    block->pFrameBuffer,
    block->pCodecCtx->pix_fmt,
    width, height,
    align
);
block->sws = sws_getContext(
    width, height,
    AV_PIX_FMT_YUV420P,
    width, height,
    AV_PIX_FMT_RGB32,
    SWS_BILINEAR, NULL, NULL, 0
);


  


  Wildcards are that :

  


  

  • I'm using React-Native

  


  • My emulator is x86 android api 28

  


  • My real-device is arm64-v8a AOSP (around api 28, don't remember exactly(

  


  


  Other notes :

  


  

  • libav .so files are compiled from mobile-ffmpeg project.

  


  • I can also sws_scale also works on x86_64 linux using SDL to project YV12

  


  • Test video is here : https://github.com/markkimsal/video-thumbnailer/tree/master/fixtures

  


  • block is a simple C struct with pointers to relevant AV memory structures.

  


  • Using FFMPEG 4.3.2

  


  


  I'm pretty certain it has something to do with the pixel alignment. But documentation is practically non-existent on this topic. It could also be the difference between pixel formats RGBA and RGB32, or possibly little-endian vs big-endian.

  


• IP-Cam / CCTV-Cam Live Streaming on iPhone/iPad

  19 mai 2013, par user1744691

  I want to get stream of an ip-cam on my iPhone/iPad and want to display it on screen. By R&D i found that ffmpeg is the only way to achieve it but i found nothing on ffmpeg. Is there any other way to achieve it or a confirmed way to get compiled ffmpeg on mac please mention that. Material regarding how to use ffmepg or source code example will be highly appreciated.

  Is there nothing built-in framework to achieve it if not then please mention if there is any free framework/sdk to achieve this functionality.

  Thanks

• Using FFMPEG for crossplatform hardware decoding of MPEG streams

  5 février 2019, par Kamille

  The application I am working on is targeted for the Windows (10) platform as well as the Linux (Ubuntu 18.04) platform.
  We need support for hardware encoding/decoding of H264 and HEVC.

  My question is :
  Should I use the available SDK’s for the graphics card (in our case NVIDIA) or
  can I somehow use the FFMPEG SDK to do the job ? And in the latter case is there
  some guidline or example material available ?

  I expect using the graphics card SDK to be much more work but on the other hand I couldn’t find any usable examples for the FFMPEG option ?