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Diffstat (limited to 'gpr/source/lib/vc5_common/codec.c')
| -rwxr-xr-x | gpr/source/lib/vc5_common/codec.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/gpr/source/lib/vc5_common/codec.c b/gpr/source/lib/vc5_common/codec.c new file mode 100755 index 0000000..2308f75 --- /dev/null +++ b/gpr/source/lib/vc5_common/codec.c @@ -0,0 +1,201 @@ +/*! @file codec.c + * + * @brief Implementation of functions that are common to the + * reference decoder and encoder + * + * @version 1.0.0 + * + * (C) Copyright 2018 GoPro Inc (http://gopro.com/). + * + * Licensed under either: + * - Apache License, Version 2.0, http://www.apache.org/licenses/LICENSE-2.0 + * - MIT license, http://opensource.org/licenses/MIT + * at your option. + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include "common.h" + +/*! + @brief Initialize the codec state to before encoding or decoding the bitstream + + Most of the codec state can be deduced from the decoding parameters. + For example, the dimensions of the first wavelet band in the bitstream + can be deduced from the encoded frame dimensions and the structure of + the wavelet tree. + + The encoder will not insert parameters into the bitstream if the values + of the parameters are the same as in the codec state. This routine + should initialize the codec state with correct values if those values + can be inferred by the decoder, otherwise the use incorrect or default + values. + + Note that the default encoded format is YUV 4:2:2, but this format is not + supported by the baseline profile encoder so the encoded format must be + explicitly written into the bitstream. + + @todo Add more default values required to properly initialize the codec state. +*/ +CODEC_ERROR PrepareCodecState(CODEC_STATE *codec) +{ + // Initialize the channel to channel number zero + codec->channel_number = 0; + + // Initialize the subband number to subband zero (the lowpass band) + codec->subband_number = 0; + + // The number of subbands per channel is a constant + codec->subband_count = 10; + + // The default precision of pixels in the input frame is ten bits + codec->bits_per_component = 12; + + // Force the encoder to insert the encoded dimensions into the bitstream + //codec->encoded.width = 0; + //codec->encoded.height = 0; + + /* + TODO: Do not have to encode the display dimensions into the bitstream if the decoder + can infer the display dimensions from the encoded dimensions and format, but must + encode the display dimensions if the encoded dimensions include padding. + + TODO: Check that this matches the current decoder implementation. + */ + + // Set the default precision for encoding lowpass band coefficients + codec->lowpass_precision = 16; + + //TODO: Set more default values in the codec state + + return CODEC_ERROR_OKAY; +} + +/*! + @brief Reformat a segment value into the encoder version + + The version of the encoder that created the clip may be encoded into every sample. + + @todo Document the encoder version number format +*/ +uint32_t EncoderVersion(uint32_t value) +{ + return (((value >> 12) & 0x0F) << 16) | + (((value >> 8) & 0x0F) << 8) | + ((value) & 0xFF); +} + +/*! + @brief Unpack the version tag value into its components +*/ +void SetCodecVersion(uint8_t version[3], uint16_t value) +{ + version[0] = (uint8_t)((value >> 12) & 0x0F); // Major version + version[1] = (uint8_t)((value >> 8) & 0x0F); // Minor version + version[2] = (uint8_t)(value & 0xFF); // Revision +} + +#if VC5_ENABLED_PART(VC5_PART_IMAGE_FORMATS) +/*! + @brief Return true if the image format is valid +*/ +bool ValidImageFormat(IMAGE_FORMAT image_format) +{ + if (0 < image_format && image_format < IMAGE_FORMAT_COUNT) { + return true; + } + return false; +} +#endif + +/*! + @brief Unpack the tag value into the prescale table + + The prescale table contains the prescale value for each wavelet in the + transform. The prescale value is a right shift that is applied to the + input data before the wavelet is computed. + + The prescale table is used for all transforms and does not depend on the + channel number. +*/ +CODEC_ERROR UpdatePrescaleTable(CODEC_STATE *codec, TAGWORD value) +{ + int wavelet_index; + + for (wavelet_index = 0; wavelet_index < MAX_WAVELET_COUNT; wavelet_index++) + { + // Unpack the prescale value + int prescale_value = (value >> (14 - wavelet_index * 2)) & 0x03; + assert(0 <= prescale_value && prescale_value < UINT8_MAX); + + // Store the prescale value in the codec state + codec->prescale_table[wavelet_index] = (uint_fast8_t)prescale_value; + } + + return CODEC_ERROR_OKAY; +} + +/*! + @brief Update the flags that describe the frame structure + + The frame structure includes characteristics such as interlaced versus + progressive and top or bottom field first. +*/ +CODEC_ERROR UpdateFrameStructureFlags(CODEC_STATE *codec, TAGWORD value) +{ + codec->progressive = !(value & IMAGE_STRUCTURE_INTERLACED); + codec->top_field_first = !(value & IMAGE_STRUCTURE_BOTTOM_FIELD_FIRST); + codec->frame_inverted = (value & IMAGE_STRUCTURE_BOTTOM_ROW_FIRST); + + return CODEC_ERROR_OKAY; +} + +/*! + @brief Initialize the codec state using the default constructor + + This routine is like a default constructor in C++ as it guarantees that + the codec state is initialized to a know starting state with all pointers + set to NULL and all counters set to zero. + + The routine @ref PrepareCodecState is used to set default values for the + codec state prior to decoding a sample. +*/ +CODEC_ERROR InitCodecState(CODEC_STATE *state) +{ + // Clear the codec state + memset(state, 0, sizeof(CODEC_STATE)); + return CODEC_ERROR_OKAY; +} + +/*! + @brief Set the flags that determine the band coding + + There can be up to 15 different codebooks as specified by the lower + four bigs in the band coding flags. Use the default codebook if the + active codebook is zero. + + The baseline profile does not allow difference coding or alternative + codebooks. +*/ +CODEC_ERROR SetBandCoding(CODEC_STATE *codec, TAGWORD value) +{ + (void) codec; + return CODEC_ERROR_OKAY; +} + +/*! + @brief Return true if the specified part is enabled at runtime + + This predicate is used to test whether a specific part in the VC-5 standard is + enabled at runtime by this codec implementation. + +*/ +bool IsPartEnabled(ENABLED_PARTS enabled_parts, int part_number) +{ + return ((enabled_parts & VC5_PART_MASK(part_number)) != 0); +} + |