// Point-sampling U/V sampler.
static int EmitSampledRGB(VP8Io* io, WebPDecParams* p) {
WebPDecBuffer* output = p.output;
WebPRGBABuffer* buf = &output.u.RGBA;
byte* dst = buf.rgba + io.mb_y * buf.stride;
byte* y_src = io.y;
byte* u_src = io.u;
byte* v_src = io.v;
WebPSampleLinePairFunc sample =
io.a ? WebPSamplersKeepAlpha[output.colorspace]
: WebPSamplers[output.colorspace];
int mb_w = io.mb_w;
int last = io.mb_h - 1;
int j;
for (j = 0; j < last; j += 2) {
sample(y_src, y_src + io.y_stride, u_src, v_src,
dst, dst + buf.stride, mb_w);
y_src += 2 * io.y_stride;
u_src += io.uv_stride;
v_src += io.uv_stride;
dst += 2 * buf.stride;
}
if (j == last) { // Just do the last line twice
sample(y_src, y_src, u_src, v_src, dst, dst, mb_w);
}
return io.mb_h;
}
//------------------------------------------------------------------------------
// "Into" decoding variants
// Main flow
static VP8StatusCode DecodeInto(byte* data, uint data_size,
WebPDecParams* params)
{
VP8Decoder* dec = VP8New();
VP8StatusCode status = VP8_STATUS_OK;
VP8Io io;
assert(params);
if (dec == null) {
return VP8_STATUS_INVALID_PARAM;
}
VP8InitIo(&io);
io.data = data;
io.data_size = data_size;
WebPInitCustomIo(params, &io); // Plug the I/O functions.
#if WEBP_USE_THREAD
dec.use_threads_ = params.options && (params.options.use_threads > 0);
#else
dec.use_threads_ = 0;
#endif
// Decode bitstream header, update io.width/io.height.
if (!VP8GetHeaders(dec, &io)) {
status = VP8_STATUS_BITSTREAM_ERROR;
} else {
// Allocate/check output buffers.
status = WebPAllocateDecBuffer(io.width, io.height, params.options,
params.output);
if (status == VP8_STATUS_OK) {
// Decode
if (!VP8Decode(dec, &io)) {
status = dec.status_;
}
}
}
VP8Delete(dec);
if (status != VP8_STATUS_OK) {
WebPFreeDecBuffer(params.output);
}
return status;
}
//------------------------------------------------------------------------------
// Main YUV<.RGB conversion functions
static int EmitYUV(VP8Io* io, WebPDecParams* p) {
WebPDecBuffer* output = p.output;
WebPYUVABuffer* buf = &output.u.YUVA;
byte* y_dst = buf.y + io.mb_y * buf.y_stride;
byte* u_dst = buf.u + (io.mb_y >> 1) * buf.u_stride;
byte* v_dst = buf.v + (io.mb_y >> 1) * buf.v_stride;
int mb_w = io.mb_w;
int mb_h = io.mb_h;
int uv_w = (mb_w + 1) / 2;
int uv_h = (mb_h + 1) / 2;
int j;
for (j = 0; j < mb_h; ++j) {
memcpy(y_dst + j * buf.y_stride, io.y + j * io.y_stride, mb_w);
}
for (j = 0; j < uv_h; ++j) {
memcpy(u_dst + j * buf.u_stride, io.u + j * io.uv_stride, uv_w);
memcpy(v_dst + j * buf.v_stride, io.v + j * io.uv_stride, uv_w);
}
return io.mb_h;
}
//------------------------------------------------------------------------------
// YUV444 . RGB conversion
#if false // TODO(skal): this is for future rescaling.
static int EmitRGB(VP8Io* io, WebPDecParams* p) {
WebPDecBuffer* output = p.output;
WebPRGBABuffer* buf = &output.u.RGBA;
byte* dst = buf.rgba + io.mb_y * buf.stride;
byte* y_src = io.y;
byte* u_src = io.u;
byte* v_src = io.v;
WebPYUV444Converter convert = WebPYUV444Converters[output.colorspace];
int mb_w = io.mb_w;
int last = io.mb_h;
int j;
for (j = 0; j < last; ++j) {
convert(y_src, u_src, v_src, dst, mb_w);
y_src += io.y_stride;
u_src += io.uv_stride;
v_src += io.uv_stride;
dst += buf.stride;
}
return io.mb_h;
}
static int EmitRescaledRGB(VP8Io* io, WebPDecParams* p) {
int mb_h = io.mb_h;
int uv_mb_h = (mb_h + 1) >> 1;
int j = 0, uv_j = 0;
int num_lines_out = 0;
while (j < mb_h) {
int y_lines_in = Import(io.y + j * io.y_stride, io.y_stride,
mb_h - j, &p.scaler_y);
int u_lines_in = Import(io.u + uv_j * io.uv_stride, io.uv_stride,
uv_mb_h - uv_j, &p.scaler_u);
int v_lines_in = Import(io.v + uv_j * io.uv_stride, io.uv_stride,
uv_mb_h - uv_j, &p.scaler_v);
(void)v_lines_in; // remove a gcc warning
assert(u_lines_in == v_lines_in);
j += y_lines_in;
uv_j += u_lines_in;
num_lines_out += ExportRGB(p, num_lines_out);
}
return num_lines_out;
}
//------------------------------------------------------------------------------
// Fancy upsampling
#if FANCY_UPSAMPLING
static int EmitFancyRGB(VP8Io* io, WebPDecParams* p) {
int num_lines_out = io.mb_h; // a priori guess
WebPRGBABuffer* buf = &p.output.u.RGBA;
byte* dst = buf.rgba + io.mb_y * buf.stride;
WebPUpsampleLinePairFunc upsample =
io.a ? WebPUpsamplersKeepAlpha[p.output.colorspace]
: WebPUpsamplers[p.output.colorspace];
byte* cur_y = io.y;
byte* cur_u = io.u;
byte* cur_v = io.v;
byte* top_u = p.tmp_u;
byte* top_v = p.tmp_v;
int y = io.mb_y;
int y_end = io.mb_y + io.mb_h;
int mb_w = io.mb_w;
int uv_w = (mb_w + 1) / 2;
if (y == 0) {
// First line is special cased. We mirror the u/v samples at boundary.
upsample(null, cur_y, cur_u, cur_v, cur_u, cur_v, null, dst, mb_w);
} else {
// We can finish the left-over line from previous call.
// Warning! Don't overwrite the alpha values (if any), as they
// are not lagging one line behind but are already written.
upsample(p.tmp_y, cur_y, top_u, top_v, cur_u, cur_v,
dst - buf.stride, dst, mb_w);
++num_lines_out;
}
// Loop over each output pairs of row.
for (; y + 2 < y_end; y += 2) {
top_u = cur_u;
top_v = cur_v;
cur_u += io.uv_stride;
cur_v += io.uv_stride;
dst += 2 * buf.stride;
cur_y += 2 * io.y_stride;
upsample(cur_y - io.y_stride, cur_y,
top_u, top_v, cur_u, cur_v,
dst - buf.stride, dst, mb_w);
}
// move to last row
cur_y += io.y_stride;
if (io.crop_top + y_end < io.crop_bottom) {
// Save the unfinished samples for next call (as we're not done yet).
memcpy(p.tmp_y, cur_y, mb_w * sizeof(*p.tmp_y));
memcpy(p.tmp_u, cur_u, uv_w * sizeof(*p.tmp_u));
memcpy(p.tmp_v, cur_v, uv_w * sizeof(*p.tmp_v));
// The fancy upsampler leaves a row unfinished behind
// (except for the very last row)
num_lines_out--;
} else {
// Process the very last row of even-sized picture
if (!(y_end & 1)) {
upsample(cur_y, null, cur_u, cur_v, cur_u, cur_v,
dst + buf.stride, null, mb_w);
}
}
return num_lines_out;
}
//------------------------------------------------------------------------------
// Main entry point
void WebPInitCustomIo(WebPDecParams* params, VP8Io* io) {
io.put = CustomPut;
io.setup = CustomSetup;
io.teardown = CustomTeardown;
io.opaque = params;
}
static int EmitRescaledAlphaRGB(VP8Io* io, WebPDecParams* p) {
if (io.a != null) {
int (* output_func)(WebPDecParams* const, int) =
(p.output.colorspace == MODE_RGBA_4444) ? ExportAlphaRGBA4444
: ExportAlpha;
WebPRescaler* scaler = &p.scaler_a;
int j = 0, pos = 0;
while (j < io.mb_h) {
j += Import(io.a + j * io.width, io.width, io.mb_h - j, scaler);
pos += output_func(p, pos);
}
}
return 0;
}
static int InitRGBRescaler(VP8Io* io, WebPDecParams* p) {
int has_alpha = IsAlphaMode(p.output.colorspace);
int out_width = io.scaled_width;
int out_height = io.scaled_height;
int uv_in_width = (io.mb_w + 1) >> 1;
int uv_in_height = (io.mb_h + 1) >> 1;
uint work_size = 2 * out_width; // scratch memory for one rescaler
int* work; // rescalers work area
byte* tmp; // tmp storage for scaled YUV444 samples before RGB conversion
uint tmp_size1, tmp_size2;
tmp_size1 = 3 * work_size;
tmp_size2 = 3 * out_width;
if (has_alpha) {
tmp_size1 += work_size;
tmp_size2 += out_width;
}
p.memory =
calloc(1, tmp_size1 * sizeof(*work) + tmp_size2 * sizeof(*tmp));
if (p.memory == null) {
return 0; // memory error
}
work = (int*)p.memory;
tmp = (byte*)(work + tmp_size1);
InitRescaler(&p.scaler_y, io.mb_w, io.mb_h,
tmp + 0 * out_width, out_width, out_height, 0,
io.mb_w, out_width, io.mb_h, out_height,
work + 0 * work_size);
InitRescaler(&p.scaler_u, uv_in_width, uv_in_height,
tmp + 1 * out_width, out_width, out_height, 0,
io.mb_w, 2 * out_width, io.mb_h, 2 * out_height,
work + 1 * work_size);
InitRescaler(&p.scaler_v, uv_in_width, uv_in_height,
tmp + 2 * out_width, out_width, out_height, 0,
io.mb_w, 2 * out_width, io.mb_h, 2 * out_height,
work + 2 * work_size);
p.emit = EmitRescaledRGB;
if (has_alpha) {
InitRescaler(&p.scaler_a, io.mb_w, io.mb_h,
tmp + 3 * out_width, out_width, out_height, 0,
io.mb_w, out_width, io.mb_h, out_height,
work + 3 * work_size);
p.emit_alpha = EmitRescaledAlphaRGB;
}
return 1;
}
// FANCY_UPSAMPLING
//------------------------------------------------------------------------------
static int EmitAlphaYUV(VP8Io* io, WebPDecParams* p) {
byte* alpha = io.a;
if (alpha != null) {
int j;
int mb_w = io.mb_w;
int mb_h = io.mb_h;
WebPYUVABuffer* buf = &p.output.u.YUVA;
byte* dst = buf.a + io.mb_y * buf.a_stride;
for (j = 0; j < mb_h; ++j) {
memcpy(dst, alpha, mb_w * sizeof(*dst));
alpha += io.width;
dst += buf.a_stride;
}
}
return 0;
}
static int ExportAlphaRGBA4444(WebPDecParams* p, int y_pos) {
WebPRGBABuffer* buf = &p.output.u.RGBA;
byte* dst = buf.rgba + (p.last_y + y_pos) * buf.stride + 1;
int num_lines_out = 0;
while (p.scaler_a.y_accum <= 0) {
int i;
assert(p.last_y + y_pos + num_lines_out < p.output.height);
ExportRow(&p.scaler_a);
for (i = 0; i < p.scaler_a.dst_width; ++i) {
// Fill in the alpha value (converted to 4 bits).
uint alpha_val = clip((p.scaler_a.dst[i] + 8) >> 4, 15);
dst[2 * i] = (dst[2 * i] & 0xf0) | alpha_val;
}
dst += buf.stride;
++num_lines_out;
}
return num_lines_out;
}
static int ExportRGB(WebPDecParams* p, int y_pos) {
WebPYUV444Converter convert =
WebPYUV444Converters[p.output.colorspace];
WebPRGBABuffer* buf = &p.output.u.RGBA;
byte* dst = buf.rgba + (p.last_y + y_pos) * buf.stride;
int num_lines_out = 0;
// For RGB rescaling, because of the YUV420, current scan position
// U/V can be +1/-1 line from the Y one. Hence the double test.
while (p.scaler_y.y_accum <= 0 && p.scaler_u.y_accum <= 0) {
assert(p.last_y + y_pos + num_lines_out < p.output.height);
assert(p.scaler_u.y_accum == p.scaler_v.y_accum);
ExportRow(&p.scaler_y);
ExportRow(&p.scaler_u);
ExportRow(&p.scaler_v);
convert(p.scaler_y.dst, p.scaler_u.dst, p.scaler_v.dst,
dst, p.scaler_y.dst_width);
dst += buf.stride;
++num_lines_out;
}
return num_lines_out;
}
//------------------------------------------------------------------------------
// WebPDecParams
void WebPResetDecParams(WebPDecParams* params)
{
if (params) {
memset(params, 0, sizeof(*params));
}
}
static int InitYUVRescaler(VP8Io* io, WebPDecParams* p) {
int has_alpha = IsAlphaMode(p.output.colorspace);
WebPYUVABuffer* buf = &p.output.u.YUVA;
int out_width = io.scaled_width;
int out_height = io.scaled_height;
int uv_out_width = (out_width + 1) >> 1;
int uv_out_height = (out_height + 1) >> 1;
int uv_in_width = (io.mb_w + 1) >> 1;
int uv_in_height = (io.mb_h + 1) >> 1;
uint work_size = 2 * out_width; // scratch memory for luma rescaler
uint uv_work_size = 2 * uv_out_width; // and for each u/v ones
uint tmp_size;
int* work;
tmp_size = work_size + 2 * uv_work_size;
if (has_alpha) {
tmp_size += work_size;
}
p.memory = calloc(1, tmp_size * sizeof(*work));
if (p.memory == null) {
return 0; // memory error
}
work = (int*)p.memory;
InitRescaler(&p.scaler_y, io.mb_w, io.mb_h,
buf.y, out_width, out_height, buf.y_stride,
io.mb_w, out_width, io.mb_h, out_height,
work);
InitRescaler(&p.scaler_u, uv_in_width, uv_in_height,
buf.u, uv_out_width, uv_out_height, buf.u_stride,
uv_in_width, uv_out_width,
uv_in_height, uv_out_height,
work + work_size);
InitRescaler(&p.scaler_v, uv_in_width, uv_in_height,
buf.v, uv_out_width, uv_out_height, buf.v_stride,
uv_in_width, uv_out_width,
uv_in_height, uv_out_height,
work + work_size + uv_work_size);
p.emit = EmitRescaledYUV;
if (has_alpha) {
InitRescaler(&p.scaler_a, io.mb_w, io.mb_h,
buf.a, out_width, out_height, buf.a_stride,
io.mb_w, out_width, io.mb_h, out_height,
work + work_size + 2 * uv_work_size);
p.emit_alpha = EmitRescaledAlphaYUV;
}
return 1;
}
static int EmitAlphaRGB(VP8Io* io, WebPDecParams* p) {
int mb_w = io.mb_w;
int mb_h = io.mb_h;
int i, j;
WebPRGBABuffer* buf = &p.output.u.RGBA;
byte* dst = buf.rgba + io.mb_y * buf.stride +
(p.output.colorspace == MODE_ARGB ? 0 : 3);
byte* alpha = io.a;
if (alpha) {
for (j = 0; j < mb_h; ++j) {
for (i = 0; i < mb_w; ++i) {
dst[4 * i] = alpha[i];
}
alpha += io.width;
dst += buf.stride;
}
}
return 0;
}
static int EmitRescaledAlphaYUV(VP8Io* io, WebPDecParams* p) {
if (io.a != null) {
Rescale(io.a, io.width, io.mb_h, &p.scaler_a);
}
return 0;
}
static int EmitRescaledYUV(VP8Io* io, WebPDecParams* p) {
int mb_h = io.mb_h;
int uv_mb_h = (mb_h + 1) >> 1;
int num_lines_out = Rescale(io.y, io.y_stride, mb_h, &p.scaler_y);
Rescale(io.u, io.uv_stride, uv_mb_h, &p.scaler_u);
Rescale(io.v, io.uv_stride, uv_mb_h, &p.scaler_v);
return num_lines_out;
}
static int EmitAlphaRGBA4444(VP8Io* io, WebPDecParams* p) {
int mb_w = io.mb_w;
int mb_h = io.mb_h;
int i, j;
WebPRGBABuffer* buf = &p.output.u.RGBA;
byte* dst = buf.rgba + io.mb_y * buf.stride + 1;
byte* alpha = io.a;
if (alpha) {
for (j = 0; j < mb_h; ++j) {
for (i = 0; i < mb_w; ++i) {
// Fill in the alpha value (converted to 4 bits).
uint alpha_val = clip((alpha[i] + 8) >> 4, 15);
dst[2 * i] = (dst[2 * i] & 0xf0) | alpha_val;
}
alpha += io.width;
dst += buf.stride;
}
}
return 0;
}
int VP8_FRAME_HEADER_SIZE = 10; // Size of the frame header within VP8 data.
#endregion Fields
#region Methods
// Should be called first, before any use of the WebPDecParams object.
void WebPResetDecParams(WebPDecParams* params);
static int ExportAlpha(WebPDecParams* p, int y_pos) {
WebPRGBABuffer* buf = &p.output.u.RGBA;
byte* dst = buf.rgba + (p.last_y + y_pos) * buf.stride +
(p.output.colorspace == MODE_ARGB ? 0 : 3);
int num_lines_out = 0;
while (p.scaler_a.y_accum <= 0) {
int i;
assert(p.last_y + y_pos + num_lines_out < p.output.height);
ExportRow(&p.scaler_a);
for (i = 0; i < p.scaler_a.dst_width; ++i) {
dst[4 * i] = p.scaler_a.dst[i];
}
dst += buf.stride;
++num_lines_out;
}
return num_lines_out;
}