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VP8GetInfo() + WebPResetDecParams()

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- add an internal VP8GetInfo() to parse header
- add WebPResetDecParams() for proper initialization

Change-Id: Ic39ea634d1d8016d25bdcfef2cb0d00b6dad83e9
This commit is contained in:
Pascal Massimino 2011-05-19 19:07:01 -07:00
parent 416b7a6b95
commit 92e5c6e1d4
5 changed files with 75 additions and 52 deletions
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2
src/dec/idec.c
View File

@ -429,6 +429,8 @@ WebPIDecoder* WebPINew(WEBP_CSP_MODE mode) {
}
idec->state_ = STATE_HEADER;
WebPResetDecParams(&idec->params_);
idec->params_.mode = mode;
InitMemBuffer(&idec->mem_);

38
src/dec/vp8.c
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@ -74,6 +74,44 @@ int VP8SetError(VP8Decoder* const dec,
return 0;
}
//-----------------------------------------------------------------------------
int VP8GetInfo(const uint8_t* data, uint32_t chunk_size,
int *width, int *height) {
// check signature
if (data[3] != 0x9d || data[4] != 0x01 || data[5] != 0x2a) {
return 0; // Wrong signature.
} else {
const uint32_t bits = data[0] | (data[1] << 8) | (data[2] << 16);
const int key_frame = !(bits & 1);
const int w = ((data[7] << 8) | data[6]) & 0x3fff;
const int h = ((data[9] << 8) | data[8]) & 0x3fff;
if (!key_frame) { // Not a keyframe.
return 0;
}
if (((bits >> 1) & 7) > 3) {
return 0; // unknown profile
}
if (!((bits >> 4) & 1)) {
return 0; // first frame is invisible!
}
if (((bits >> 5)) >= chunk_size) { // partition_length
return 0; // inconsistent size information.
}
if (width) {
*width = w;
}
if (height) {
*height = h;
}
return 1;
}
}
//-----------------------------------------------------------------------------
// Header parsing

5
src/dec/vp8i.h
View File

@ -263,6 +263,11 @@ struct VP8Decoder {
// in vp8.c
int VP8SetError(VP8Decoder* const dec,
VP8StatusCode error, const char * const msg);
// Validates the VP8 data-header and retrieve basic header information viz width
// and height. Returns 0 in case of formatting error. *width/*height can be
// passed NULL.
int VP8GetInfo(const uint8_t* data, uint32_t data_size,
int *width, int *height);
// in tree.c
void VP8ResetProba(VP8Proba* const proba);

79
src/dec/webp.c
View File

@ -414,18 +414,23 @@ int WebPCheckDecParams(const VP8Io* io, const WebPDecParams* params) {
return ok;
}
void WebPResetDecParams(WebPDecParams* const params) {
assert(params);
memset(params, 0, sizeof(*params));
}
void WebPClearDecParams(WebPDecParams* params) {
assert(params);
if (!params->external_buffer) {
free(params->output);
}
memset(params, 0, sizeof(*params));
WebPResetDecParams(params);
}
//-----------------------------------------------------------------------------
// "Into" variants
static uint8_t* DecodeInto(WEBP_CSP_MODE mode,
const uint8_t* data, uint32_t data_size,
static uint8_t* DecodeInto(const uint8_t* data, uint32_t data_size,
WebPDecParams* params) {
VP8Decoder* dec = VP8New();
VP8Io io;
@ -439,7 +444,6 @@ static uint8_t* DecodeInto(WEBP_CSP_MODE mode,
io.data = data;
io.data_size = data_size;
params->mode = mode;
io.opaque = params;
WebPInitCustomIo(&io);
@ -455,7 +459,7 @@ static uint8_t* DecodeInto(WEBP_CSP_MODE mode,
return NULL;
}
if (mode != MODE_YUV) {
if (params->mode != MODE_YUV) {
VP8YUVInit();
}
@ -473,12 +477,12 @@ uint8_t* WebPDecodeRGBInto(const uint8_t* data, uint32_t data_size,
return NULL;
}
WebPResetDecParams(&params);
params.mode = MODE_RGB;
params.output = output;
params.stride = output_stride;
params.output_size = output_size;
params.output_u_size = 0;
params.output_v_size = 0;
return DecodeInto(MODE_RGB, data, data_size, &params);
return DecodeInto(data, data_size, &params);
}
uint8_t* WebPDecodeRGBAInto(const uint8_t* data, uint32_t data_size,
@ -490,12 +494,12 @@ uint8_t* WebPDecodeRGBAInto(const uint8_t* data, uint32_t data_size,
return NULL;
}
WebPResetDecParams(&params);
params.mode = MODE_RGBA;
params.output = output;
params.stride = output_stride;
params.output_size = output_size;
params.output_u_size = 0;
params.output_v_size = 0;
return DecodeInto(MODE_RGBA, data, data_size, &params);
return DecodeInto(data, data_size, &params);
}
uint8_t* WebPDecodeBGRInto(const uint8_t* data, uint32_t data_size,
@ -507,12 +511,12 @@ uint8_t* WebPDecodeBGRInto(const uint8_t* data, uint32_t data_size,
return NULL;
}
WebPResetDecParams(&params);
params.mode = MODE_BGR;
params.output = output;
params.stride = output_stride;
params.output_size = output_size;
params.output_u_size = 0;
params.output_v_size = 0;
return DecodeInto(MODE_BGR, data, data_size, &params);
return DecodeInto(data, data_size, &params);
}
uint8_t* WebPDecodeBGRAInto(const uint8_t* data, uint32_t data_size,
@ -524,12 +528,12 @@ uint8_t* WebPDecodeBGRAInto(const uint8_t* data, uint32_t data_size,
return NULL;
}
WebPResetDecParams(&params);
params.mode = MODE_BGRA;
params.output = output;
params.stride = output_stride;
params.output_size = output_size;
params.output_u_size = 0;
params.output_v_size = 0;
return DecodeInto(MODE_BGRA, data, data_size, &params);
return DecodeInto(data, data_size, &params);
}
uint8_t* WebPDecodeYUVInto(const uint8_t* data, uint32_t data_size,
@ -542,6 +546,8 @@ uint8_t* WebPDecodeYUVInto(const uint8_t* data, uint32_t data_size,
return NULL;
}
WebPResetDecParams(&params);
params.mode = MODE_YUV;
params.output = luma;
params.stride = luma_stride;
params.output_size = luma_size;
@ -551,7 +557,7 @@ uint8_t* WebPDecodeYUVInto(const uint8_t* data, uint32_t data_size,
params.v = v;
params.v_stride = v_stride;
params.output_v_size = v_size;
return DecodeInto(MODE_YUV, data, data_size, &params);
return DecodeInto(data, data_size, &params);
}
//-----------------------------------------------------------------------------
@ -562,7 +568,7 @@ static uint8_t* Decode(WEBP_CSP_MODE mode, const uint8_t* data,
uint8_t* output;
WebPDecParams params;
memset(&params, 0, sizeof(params));
WebPResetDecParams(&params);
params.mode = mode;
if (!WebPInitDecParams(data, data_size, width, height, &params)) {
return NULL;
@ -571,7 +577,7 @@ static uint8_t* Decode(WEBP_CSP_MODE mode, const uint8_t* data,
params.output_size = params.stride * (*height);
params.output_u_size = params.output_v_size =
params.u_stride * ((*height + 1) / 2);
output = DecodeInto(mode, data, data_size, &params);
output = DecodeInto(data, data_size, &params);
if (!output) {
WebPClearDecParams(&params);
}
@ -631,38 +637,7 @@ int WebPGetInfo(const uint8_t* data, uint32_t data_size,
if (data_size < 10) {
return 0; // not enough data
}
// check signature
if (data[3] != 0x9d || data[4] != 0x01 || data[5] != 0x2a) {
return 0; // Wrong signature.
} else {
const uint32_t bits = data[0] | (data[1] << 8) | (data[2] << 16);
const int key_frame = !(bits & 1);
const int w = ((data[7] << 8) | data[6]) & 0x3fff;
const int h = ((data[9] << 8) | data[8]) & 0x3fff;
if (!key_frame) { // Not a keyframe.
return 0;
}
if (((bits >> 1) & 7) > 3) {
return 0; // unknown profile
}
if (!((bits >> 4) & 1)) {
return 0; // first frame is invisible!
}
if (((bits >> 5)) >= chunk_size) { // partition_length
return 0; // inconsistent size information.
}
if (width) {
*width = w;
}
if (height) {
*height = h;
}
return 1;
}
return VP8GetInfo(data, chunk_size, width, height);
}
#if defined(__cplusplus) || defined(c_plusplus)

3
src/dec/webpi.h
View File

@ -34,6 +34,9 @@ typedef struct {
int external_buffer; // If true, the output buffers are externally owned
} WebPDecParams;
// Should be called first, before any use of the WebPDecParams object.
void WebPResetDecParams(WebPDecParams* const params);
// If a RIFF container is detected, validate it and skip over it. Returns
// VP8 bit-stream size if RIFF header is valid else returns 0
uint32_t WebPCheckRIFFHeader(const uint8_t** data_ptr,