filmstro_ffmpeg_FFmpegVideoScaler.h

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/*
 ==============================================================================
 Copyright (c) 2017, Filmstro Ltd. - Daniel Walz
 All rights reserved.

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 are permitted provided that the following conditions are met:
 1. Redistributions of source code must retain the above copyright notice, this
    list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.
 3. Neither the name of the copyright holder nor the names of its contributors
    may be used to endorse or promote products derived from this software without
    specific prior written permission.

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 ==============================================================================
 \class        FFmpegVideoScaler
 \file         filmstro_ffmpeg_FFmpegVideoScaler.h
 \brief        Converts and scales FFmpeg frames into juce format

 \author       Daniel Walz @ filmstro.com
 \date         January 25th 2017

 \description  Converts and scales FFmpeg frames into juce format

 ==============================================================================
 */


#ifndef FILMSTRO_FFMPEG_FFMPEGVIDEOSCALER_H_INCLUDED
#define FILMSTRO_FFMPEG_FFMPEGVIDEOSCALER_H_INCLUDED

class FFmpegVideoScaler {
public:
    FFmpegVideoScaler () : scalerContext (nullptr) {}

    ~FFmpegVideoScaler ()
    {
        if (scalerContext)
            sws_freeContext (scalerContext);
    }

    void setupScaler (const int in_width,  const int in_height,  const AVPixelFormat in_format,
                                         const int out_width, const int out_height, const AVPixelFormat out_format)
    {
        if (scalerContext) {
            sws_freeContext (scalerContext);
            scalerContext = nullptr;
        }

        const AVPixFmtDescriptor* in_descriptor = av_pix_fmt_desc_get (in_format);
        if (!in_descriptor) {
            DBG ("No description for input pixel format");
            return;
        }
        const int in_bitsPerPixel = av_get_padded_bits_per_pixel (in_descriptor);
        for (int i=0; i < 4; ++i)
            inLinesizes [i] = i < in_descriptor->nb_components ? in_width * in_bitsPerPixel >> 3 : 0;

        const AVPixFmtDescriptor* out_descriptor = av_pix_fmt_desc_get (out_format);
        if (!out_descriptor) {
            DBG ("No description for output pixel format");
            return;
        }
        const int out_bitsPerPixel = av_get_padded_bits_per_pixel (out_descriptor);
        for (int i=0; i < 4; ++i)
            outLinesizes [i] = i < out_descriptor->nb_components ? out_width * out_bitsPerPixel >> 3 : 0;

        /* create scaling context */
        scalerContext = sws_getContext (in_width,  in_height, in_format,
                                        out_width, out_height, out_format,
                                        SWS_BILINEAR, NULL, NULL, NULL);
        if (!scalerContext) {
            DBG ("Impossible to create scale context for the conversion");
        }
    }


    void convertFrameToImage (juce::Image& image, const AVFrame* frame)
    {
        if (scalerContext) {
            juce::Image::BitmapData data (image, 0, 0,
                                          image.getWidth(),
                                          image.getHeight(),
                                          juce::Image::BitmapData::writeOnly);

            uint8_t* destination[4] = {data.data, nullptr, nullptr, nullptr};

            sws_scale (scalerContext,
                       frame->data,
                       frame->linesize,
                       0,
                       frame->height,
                       destination,
                       outLinesizes);
        }
    }


    void convertImageToFrame (AVFrame* frame, const juce::Image& image)
    {
        if (scalerContext) {
            juce::Image::BitmapData data (image, 0, 0,
                                          image.getWidth(),
                                          image.getHeight());

            uint8_t* source[4] = {data.data, nullptr, nullptr, nullptr};

            sws_scale (scalerContext,
                       source,
                       inLinesizes,
                       0,
                       image.getHeight(),
                       frame->data,
                       frame->linesize);
        }
    }


private:
    SwsContext* scalerContext;

    int         inLinesizes[4];
    int         outLinesizes[4];

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (FFmpegVideoScaler)
};

#endif /* FILMSTRO_FFMPEG_FFMPEGVIDEOSCALER_H_INCLUDED */