[FFmpeg-devel] [PATCH 2/2] fic: Support rendering cursors

[Michael Niedermayer]

On Mon, Apr 21, 2014 at 01:03:00PM -0400, Derek Buitenhuis wrote:
> Signed-off-by: Derek Buitenhuis <derek.buitenhuis at gmail.com>
> ---
>  libavcodec/fic.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 111 insertions(+), 1 deletion(-)
> 
> diff --git a/libavcodec/fic.c b/libavcodec/fic.c
> index 8862e08..9ac3335 100644
> --- a/libavcodec/fic.c
> +++ b/libavcodec/fic.c
> @@ -38,6 +38,7 @@ typedef struct FICThreadContext {
>  typedef struct FICContext {
>      AVCodecContext *avctx;
>      AVFrame *frame;
> +    AVFrame *final_frame;
>  
>      FICThreadContext *slice_data;
>      int slice_data_size;
> @@ -48,6 +49,8 @@ typedef struct FICContext {
>  
>      int aligned_width, aligned_height;
>      int num_slices, slice_h;
> +
> +    uint8_t cursor_buf[4096];
>  } FICContext;
>  
>  static const uint8_t fic_qmat_hq[64] = {
> @@ -186,6 +189,69 @@ static int fic_decode_slice(AVCodecContext *avctx, void *tdata)
>      return 0;
>  }
>  
> +static av_always_inline void fic_alpha_blend(uint8_t *dst, uint8_t *src,
> +                                             int size, uint8_t *alpha)
> +{
> +    int i;
> +
> +    for (i = 0; i < size; i++)
> +        dst[i] = (dst[i] * (256 - alpha[i]) + src[i] * alpha[i]) >> 8;

this would be simpler:
dst[i] +=  ((src[i] - dst[i]) * alpha[i]) >> 8;


> +}
> +
> +static void fic_draw_cursor(AVCodecContext *avctx, int cur_x, int cur_y)
> +{
> +    FICContext *ctx = avctx->priv_data;
> +    uint8_t *ptr    = ctx->cursor_buf;
> +    uint8_t *dstptr[3];
> +    uint8_t planes[4][1024];
> +    uint8_t chroma[3][256];
> +    int i, j, p;
> +
> +    /* Convert to YUVA444. */
> +    for (i = 0; i < 1024; i++) {

> +        planes[0][i] = av_clip_uint8((( 25 * ptr[0] + 129 * ptr[1] +  66 * ptr[2]) / 255) + 16);
> +        planes[1][i] = av_clip_uint8(((-38 * ptr[0] + 112 * ptr[1] + -74 * ptr[2]) / 255) + 128);
> +        planes[2][i] = av_clip_uint8(((-18 * ptr[0] + 112 * ptr[1] + -94 * ptr[2]) / 255) + 128);

the clipping seems redundant


> +        planes[3][i] = ptr[3];
> +
> +        ptr += 4;
> +    }
> +
> +    /* Subsample chroma. */
> +    for (i = 0; i < 32; i += 2)
> +        for (j = 0; j < 32; j += 2)
> +            for (p = 0; p < 3; p++)
> +                chroma[p][16 * (i / 2) + j / 2] = (planes[p + 1][32 *  i      + j    ] +
> +                                                   planes[p + 1][32 *  i      + j + 1] +
> +                                                   planes[p + 1][32 * (i + 1) + j    ] +
> +                                                   planes[p + 1][32 * (i + 1) + j + 1]) / 4;
> +
> +    /* Seek to x/y pos of cursor. */
> +    for (i = 0; i < 3; i++)
> +        dstptr[i] = ctx->final_frame->data[i]                        +
> +                    (ctx->final_frame->linesize[i] * (cur_y >> !!i)) +
> +                    (cur_x >> !!i) + !!i;
> +
> +    /* Copy. */
> +    for (i = 0; i < FFMIN(32, avctx->height - cur_y) - 1; i += 2) {
> +        int lsize = FFMIN(32, avctx->width - cur_x);
> +        int csize = lsize / 2;
> +
> +        fic_alpha_blend(dstptr[0],
> +                         planes[0] + i * 32, lsize, planes[3] + i * 32);
> +        fic_alpha_blend(dstptr[0] + ctx->final_frame->linesize[0],
> +                         planes[0] + (i + 1) * 32, lsize, planes[3] + (i + 1) * 32);
> +        fic_alpha_blend(dstptr[1],
> +                         chroma[0] + (i / 2) * 16, csize, chroma[2] + (i / 2) * 16);
> +        fic_alpha_blend(dstptr[2],
> +                         chroma[1] + (i / 2) * 16, csize, chroma[2] + (i / 2) * 16);
> +
> +        dstptr[0] += ctx->final_frame->linesize[0] * 2;
> +        dstptr[1] += ctx->final_frame->linesize[1];
> +        dstptr[2] += ctx->final_frame->linesize[2];
> +    }
> +}
> +
>  static int fic_decode_frame(AVCodecContext *avctx, void *data,
>                              int *got_frame, AVPacket *avpkt)
>  {
> @@ -195,6 +261,8 @@ static int fic_decode_frame(AVCodecContext *avctx, void *data,
>      int slice, nslices;
>      int msize;
>      int tsize;
> +    int cur_x, cur_y;
> +    int skip_cursor = 0;
>      uint8_t *sdata;
>  
>      if ((ret = ff_reget_buffer(avctx, ctx->frame)) < 0) {

> @@ -232,6 +300,28 @@ static int fic_decode_frame(AVCodecContext *avctx, void *data,
>          return AVERROR_INVALIDDATA;
>      }
>  
> +    if (tsize < 32) {
> +        av_log(avctx, AV_LOG_WARNING,
> +               "Cursor data too small. Skipping cursor.\n");

this could print the value that is too small

rest should be ok if it works

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Opposition brings concord. Out of discord comes the fairest harmony.
-- Heraclitus
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