On Fri, 17 May 2013 19:43:36 +0200, Kostya Shishkov <[email protected]> 
wrote:
> ---
> Maybe I'll work on encoder support as well.
> ---
>  libavcodec/proresdec.c |  112 
> ++++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 103 insertions(+), 9 deletions(-)
> 
> diff --git a/libavcodec/proresdec.c b/libavcodec/proresdec.c
> index c42e444..0d1eb7a 100644
> --- a/libavcodec/proresdec.c
> +++ b/libavcodec/proresdec.c
> @@ -134,12 +134,21 @@ static int decode_frame_header(ProresContext *ctx, 
> const uint8_t *buf,
>      ctx->chroma_factor     = (buf[12] >> 6) & 3;
>      ctx->mb_chroma_factor  = ctx->chroma_factor + 2;
>      ctx->num_chroma_blocks = (1 << ctx->chroma_factor) >> 1;
> +    ctx->alpha_info        = buf[17] & 0xf;
> +
> +    if (ctx->alpha_info > 2) {
> +        av_log(avctx, AV_LOG_ERROR, "Invalid alpha mode %d\n", 
> ctx->alpha_info);
> +        return AVERROR_INVALIDDATA;
> +    }
> +
>      switch (ctx->chroma_factor) {
>      case 2:
> -        avctx->pix_fmt = AV_PIX_FMT_YUV422P10;
> +        avctx->pix_fmt = ctx->alpha_info ? AV_PIX_FMT_YUVA422P10
> +                                         : AV_PIX_FMT_YUV422P10;
>          break;
>      case 3:
> -        avctx->pix_fmt = AV_PIX_FMT_YUV444P10;
> +        avctx->pix_fmt = ctx->alpha_info ? AV_PIX_FMT_YUVA444P10
> +                                         : AV_PIX_FMT_YUV444P10;
>          break;
>      default:
>          av_log(avctx, AV_LOG_ERROR,
> @@ -168,10 +177,6 @@ static int decode_frame_header(ProresContext *ctx, const 
> uint8_t *buf,
>      avctx->color_trc       = buf[15];
>      avctx->colorspace      = buf[16];
>  
> -    ctx->alpha_info = buf[17] & 0xf;
> -    if (ctx->alpha_info)
> -        avpriv_report_missing_feature(avctx, "Alpha channel");
> -
>      ctx->qmat_changed = 0;
>      ptr   = buf + 20;
>      flags = buf[19];
> @@ -466,6 +471,78 @@ static void decode_slice_plane(ProresContext *ctx, 
> ProresThreadData *td,
>  }
>  
>  
> +static void unpack_alpha(GetBitContext *gb, uint16_t *dst, int num_coeffs,
> +                         const int num_bits)
> +{
> +    const int mask = (1 << num_bits) - 1;
> +    int i, idx, val, alpha_val;
> +
> +    idx       = 0;
> +    alpha_val = mask;
> +    do {
> +        do {
> +            if (get_bits1(gb))
> +                val = get_bits(gb, num_bits);
> +            else {
> +                int sign;
> +                val  = get_bits(gb, num_bits == 16 ? 7 : 4);
> +                sign = val & 1;
> +                val  = (val + 2) >> 1;
> +                if (sign)
> +                    val = -val;
> +            }
> +            alpha_val = (alpha_val + val) & mask;
> +            if (num_bits == 16)
> +                dst[idx++] = alpha_val >> 6;
> +            else
> +                dst[idx++] = (alpha_val << 2) | (alpha_val >> 6);
> +            if (idx == num_coeffs - 1)
> +                break;
> +        } while (get_bits1(gb));
> +        val = get_bits(gb, 4);
> +        if (!val)
> +            val = get_bits(gb, 11);
> +        if (idx + val > num_coeffs)
> +            val = num_coeffs - idx;
> +        if (num_bits == 16)
> +            for (i = 0; i < val; i++)
> +                dst[idx++] = alpha_val >> 6;
> +        else
> +            for (i = 0; i < val; i++)
> +                dst[idx++] = (alpha_val << 2) | (alpha_val >> 6);
> +    } while (idx < num_coeffs);
> +}
> +
> +/**
> + * Decode alpha slice plane.
> + */
> +static void decode_alpha_plane(ProresContext *ctx, ProresThreadData *td,
> +                               const uint8_t *buf, int data_size,
> +                               uint16_t *out_ptr, int linesize,
> +                               int mbs_per_slice)
> +{
> +    GetBitContext gb;
> +    int i;
> +    uint16_t *block_ptr;
> +
> +    memset(td->blocks, 0, 8 * 4 * 64 * sizeof(*td->blocks));
> +
> +    init_get_bits(&gb, buf, data_size << 3);
> +
> +    if (ctx->alpha_info == 2)
> +        unpack_alpha(&gb, td->blocks, mbs_per_slice * 4 * 64, 16);
> +    else
> +        unpack_alpha(&gb, td->blocks, mbs_per_slice * 4 * 64, 8);
> +
> +    block_ptr = td->blocks;
> +
> +    for (i = 0; i < 16; i++) {
> +        memcpy(out_ptr, block_ptr, 16 * mbs_per_slice * sizeof(*out_ptr));
> +        out_ptr   += linesize >> 1;
> +        block_ptr += 16 * mbs_per_slice;
> +    }
> +}
> +
>  static int decode_slice(AVCodecContext *avctx, void *tdata)
>  {
>      ProresThreadData *td = tdata;
> @@ -476,11 +553,12 @@ static int decode_slice(AVCodecContext *avctx, void 
> *tdata)
>      int slice_num = td->slice_num;
>      int mbs_per_slice = td->slice_width;
>      const uint8_t *buf;
> -    uint8_t *y_data, *u_data, *v_data;
> +    uint8_t *y_data, *u_data, *v_data, *a_data;
>      AVFrame *pic = ctx->frame;
>      int i, sf, slice_width_factor;
> -    int slice_data_size, hdr_size, y_data_size, u_data_size, v_data_size;
> -    int y_linesize, u_linesize, v_linesize;
> +    int slice_data_size, hdr_size;
> +    int y_data_size, u_data_size, v_data_size, a_data_size;
> +    int y_linesize, u_linesize, v_linesize, a_linesize;
>  
>      buf             = ctx->slice_data[slice_num].index;
>      slice_data_size = ctx->slice_data[slice_num + 1].index - buf;
> @@ -490,19 +568,23 @@ static int decode_slice(AVCodecContext *avctx, void 
> *tdata)
>      y_data     = pic->data[0];
>      u_data     = pic->data[1];
>      v_data     = pic->data[2];
> +    a_data     = pic->data[3];
>      y_linesize = pic->linesize[0];
>      u_linesize = pic->linesize[1];
>      v_linesize = pic->linesize[2];
> +    a_linesize = pic->linesize[3];
>  
>      if (pic->interlaced_frame) {
>          if (!(pic_num ^ pic->top_field_first)) {
>              y_data += y_linesize;
>              u_data += u_linesize;
>              v_data += v_linesize;
> +            a_data += a_linesize;
>          }
>          y_linesize <<= 1;
>          u_linesize <<= 1;
>          v_linesize <<= 1;
> +        a_linesize <<= 1;
>      }
>  
>      if (slice_data_size < 6) {
> @@ -516,6 +598,8 @@ static int decode_slice(AVCodecContext *avctx, void 
> *tdata)
>      u_data_size = AV_RB16(buf + 4);
>      v_data_size = hdr_size > 7 ? AV_RB16(buf + 6) :
>          slice_data_size - y_data_size - u_data_size - hdr_size;
> +    a_data_size = slice_data_size - y_data_size - u_data_size -
> +                  v_data_size - hdr_size;
>  
>      if (hdr_size + y_data_size + u_data_size + v_data_size > slice_data_size 
> ||
>          v_data_size < 0 || hdr_size < 6) {
> @@ -560,6 +644,16 @@ static int decode_slice(AVCodecContext *avctx, void 
> *tdata)
>                         slice_width_factor + ctx->chroma_factor - 1,
>                         td->qmat_chroma_scaled, 1);
>  
> +    /* decode alpha plane if available */
> +    if (a_data && a_data_size)
> +        decode_alpha_plane(ctx, td,
> +                           buf + hdr_size + y_data_size +
> +                               u_data_size + v_data_size,
> +                           a_data_size,
> +                           (uint16_t*) (a_data + (mb_y_pos << 4) * 
> a_linesize +
> +                                        (mb_x_pos << 5)), a_linesize,
> +                           mbs_per_slice);
> +

This construct is quite unshapely and could be prettiefied.
E.g. the third parameter shares a lot of stuff with a_data_size.
The fifth parameter could be declared a temp variable.

-- 
Anton Khirnov
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