setup_scaler()

bool MayaFlux::IO::VideoStreamContext::setup_scaler ( uint32_t  target_width, uint32_t  target_height, int  target_format  )

private

Allocate and initialise the SwsContext for pixel format conversion.

Parameters

target_width	Desired output width (0 = source width).
target_height	Desired output height (0 = source height).
target_format	Desired AVPixelFormat (negative = AV_PIX_FMT_RGBA).

Returns

True on success.

Definition at line 294 of file VideoStreamContext.cpp.

{
    if (!codec_context)
        return false;
 
    if (codec_context->pix_fmt == AV_PIX_FMT_NONE) {
        m_last_error = "setup_scaler: source pix_fmt is AV_PIX_FMT_NONE — "
                       "codec has not resolved its output format yet";
        return false;
    }
 
    out_width = target_width > 0 ? target_width : width;
    out_height = target_height > 0 ? target_height : height;
    out_pixel_format = target_format >= 0
        ? target_format
        : static_cast<int>(AV_PIX_FMT_RGBA);
 
    sws_context = sws_getContext(
        static_cast<int>(width),
        static_cast<int>(height),
        codec_context->pix_fmt,
        static_cast<int>(out_width),
        static_cast<int>(out_height),
        static_cast<AVPixelFormat>(out_pixel_format),
        SWS_BILINEAR,
        nullptr, nullptr, nullptr);
 
    if (!sws_context) {
        m_last_error = "sws_getContext failed";
        return false;
    }
 
    const AVPixFmtDescriptor* desc = av_pix_fmt_desc_get(
        static_cast<AVPixelFormat>(out_pixel_format));
    if (!desc) {
        m_last_error = "setup_scaler: no descriptor for target pixel format";
        return false;
    }
 
    if (av_pix_fmt_count_planes(static_cast<AVPixelFormat>(out_pixel_format)) != 1) {
        m_last_error = std::string("setup_scaler: target format ")
            + (desc->name ? desc->name : "?")
            + " is multi-planar; the read path writes a single packed plane";
        return false;
    }
 
    out_bytes_per_pixel = static_cast<uint32_t>((av_get_bits_per_pixel(desc) + 7) / 8);
 
    out_linesize = static_cast<int>(out_width * out_bytes_per_pixel);
    int align_remainder = out_linesize % 32;
    if (align_remainder != 0)
        out_linesize += 32 - align_remainder;
 
    return true;
}

References codec_context, height, m_last_error, out_bytes_per_pixel, out_height, out_linesize, out_pixel_format, out_width, sws_context, target_format, target_height, target_width, and width.

Referenced by open(), and rebuild_scaler_from_frame().

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