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| 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #include "media/base/h264_bitstream_converter.h" | |
| 6 | |
| 7 #include "base/logging.h" | |
| 8 | |
| 9 namespace media { | |
| 10 | |
| 11 static const uint8 kStartCodePrefix[3] = {0, 0, 1}; | |
| 12 | |
| 13 // Helper function which determines whether NAL unit of given type marks | |
| 14 // access unit boundary. | |
| 15 static bool IsAccessUnitBoundaryNal(int nal_unit_type) { | |
| 16 // Check if this packet marks access unit boundary by checking the | |
| 17 // packet type. | |
| 18 if (nal_unit_type == 6 || // Supplemental enhancement information | |
| 19 nal_unit_type == 7 || // Picture parameter set | |
| 20 nal_unit_type == 8 || // Sequence parameter set | |
| 21 nal_unit_type == 9 || // Access unit delimiter | |
| 22 (nal_unit_type >= 14 && nal_unit_type <= 18)) { // Reserved types | |
| 23 return true; | |
| 24 } | |
| 25 return false; | |
| 26 } | |
| 27 | |
| 28 H264BitstreamConverter::H264BitstreamConverter() | |
| 29 : configuration_processed_(false), | |
| 30 first_nal_unit_in_access_unit_(true), | |
| 31 nal_unit_length_field_width_(0) { | |
| 32 } | |
| 33 | |
| 34 H264BitstreamConverter::~H264BitstreamConverter() {} | |
| 35 | |
| 36 uint32 H264BitstreamConverter::ParseConfigurationAndCalculateSize( | |
| 37 const uint8* configuration_record, | |
| 38 uint32 configuration_record_size) { | |
| 39 // FFmpeg's AVCodecContext's extradata field contains the Decoder Specific | |
| 40 // Information from MP4 headers that contain the H.264 SPS and PPS members. | |
| 41 // ISO 14496-15 Chapter 5.2.4 AVCDecoderConfigurationRecord. | |
| 42 // AVCConfigurationRecord must be at least 7 bytes long. | |
| 43 if (configuration_record == NULL || configuration_record_size < 7) { | |
| 44 return 0; // Error: invalid input | |
| 45 } | |
| 46 const uint8* decoder_configuration = configuration_record; | |
| 47 uint32 parameter_set_size_bytes = 0; | |
| 48 | |
| 49 // We can skip the four first bytes as they're only profile information | |
| 50 decoder_configuration += 4; | |
| 51 // Fifth byte's two LSBs contain the interleaving field's size minus one | |
| 52 uint8 size_of_len_field = (*decoder_configuration & 0x3) + 1; | |
| 53 if (size_of_len_field != 1 && size_of_len_field != 2 && | |
| 54 size_of_len_field != 4) { | |
| 55 return 0; // Error: invalid input, NAL unit field len is not correct | |
| 56 } | |
| 57 decoder_configuration++; | |
| 58 // Sixth byte's five LSBs contain the number of SPSs | |
| 59 uint8 sps_count = *decoder_configuration & 0x1F; | |
| 60 decoder_configuration++; | |
| 61 // Then we have N * SPS's with two byte length field and actual SPS | |
| 62 while (sps_count-- > 0) { | |
| 63 if ((decoder_configuration - configuration_record) + 2 > | |
| 64 static_cast<int32>(configuration_record_size)) { | |
| 65 return 0; // Error: ran out of data | |
| 66 } | |
| 67 uint16 sps_len = decoder_configuration[0] << 8 | decoder_configuration[1]; | |
| 68 decoder_configuration += 2; | |
| 69 // write the SPS to output, always with zero byte + start code prefix | |
| 70 parameter_set_size_bytes += 1 + sizeof(kStartCodePrefix); | |
| 71 decoder_configuration += sps_len; | |
| 72 parameter_set_size_bytes += sps_len; | |
| 73 } | |
| 74 // Then we have the numner of pps in one byte | |
| 75 uint8 pps_count = *decoder_configuration; | |
| 76 decoder_configuration++; | |
| 77 // And finally, we have N * PPS with two byte length field and actual PPS | |
| 78 while (pps_count-- > 0) { | |
| 79 if ((decoder_configuration - configuration_record) + 2 > | |
| 80 static_cast<int32>(configuration_record_size)) { | |
| 81 return 0; // Error: ran out of data | |
| 82 } | |
| 83 uint16 pps_len = decoder_configuration[0] << 8 | decoder_configuration[1]; | |
| 84 decoder_configuration += 2; | |
| 85 // write the SPS to output, always with zero byte + start code prefix | |
| 86 parameter_set_size_bytes += 1 + sizeof(kStartCodePrefix); | |
| 87 decoder_configuration += pps_len; | |
| 88 parameter_set_size_bytes += pps_len; | |
| 89 } | |
| 90 // We're done processing the AVCDecoderConfigurationRecord, | |
| 91 // store the needed information for parsing actual payload | |
| 92 nal_unit_length_field_width_ = size_of_len_field; | |
| 93 configuration_processed_ = true; | |
| 94 return parameter_set_size_bytes; | |
| 95 } | |
| 96 | |
| 97 uint32 H264BitstreamConverter::CalculateNeededOutputBufferSize( | |
| 98 const uint8* input, | |
| 99 uint32 input_size) const { | |
| 100 uint32 output_size = 0; | |
| 101 uint32 data_left = input_size; | |
| 102 bool first_nal_in_this_access_unit = first_nal_unit_in_access_unit_; | |
| 103 | |
| 104 if (input == NULL || input_size == 0) { | |
| 105 return 0; // Error: invalid input data | |
| 106 } | |
| 107 if (!configuration_processed_) { | |
| 108 return 0; // Error: configuration not handled, we don't know nal unit width | |
| 109 } | |
| 110 CHECK(nal_unit_length_field_width_ == 1 || | |
| 111 nal_unit_length_field_width_ == 2 || | |
| 112 nal_unit_length_field_width_ == 4); | |
| 113 | |
| 114 // Then add the needed size for the actual packet | |
| 115 while (data_left > 0) { | |
| 116 // Read the next NAL unit length from the input buffer | |
| 117 uint8 size_of_len_field; | |
| 118 uint32 nal_unit_length; | |
| 119 for (nal_unit_length = 0, size_of_len_field = nal_unit_length_field_width_; | |
| 120 size_of_len_field > 0; | |
| 121 input++, size_of_len_field--, data_left--) { | |
| 122 nal_unit_length <<= 8; | |
| 123 nal_unit_length |= *input; | |
| 124 } | |
| 125 | |
| 126 if (nal_unit_length == 0) { | |
| 127 break; // Signifies that no more data left in the buffer | |
| 128 } else if (nal_unit_length > data_left) { | |
| 129 return 0; // Error: Not enough data for correct conversion | |
| 130 } | |
| 131 data_left -= nal_unit_length; | |
| 132 | |
| 133 // five least significant bits of first NAL unit byte signify nal_unit_type | |
| 134 int nal_unit_type = *input & 0x1F; | |
| 135 if (first_nal_in_this_access_unit || | |
| 136 IsAccessUnitBoundaryNal(nal_unit_type)) { | |
| 137 output_size += 1; // Extra zero_byte for these nal units | |
| 138 first_nal_in_this_access_unit = false; | |
| 139 } | |
| 140 // Start code prefix | |
| 141 output_size += sizeof(kStartCodePrefix); | |
| 142 // Actual NAL unit size | |
| 143 output_size += nal_unit_length; | |
| 144 input += nal_unit_length; | |
| 145 // No need for trailing zero bits | |
| 146 } | |
| 147 return output_size; | |
| 148 } | |
| 149 | |
| 150 bool H264BitstreamConverter::ConvertAVCDecoderConfigurationRecordToByteStream( | |
| 151 const uint8* input, | |
| 152 uint32 input_size, | |
| 153 uint8* output, | |
| 154 uint32* output_size) { | |
| 155 uint8* outscan = output; | |
| 156 // FFmpeg's AVCodecContext's extradata field contains the Decoder Specific | |
| 157 // Information from MP4 headers that contain the H.264 SPS and PPS members. | |
| 158 // ISO 14496-15 Chapter 5.2.4 AVCDecoderConfigurationRecord. | |
| 159 const uint8* decoder_configuration = input; | |
| 160 uint32 decoderconfiguration_size = input_size; | |
| 161 uint32 out_size = 0; | |
| 162 | |
| 163 if (decoder_configuration == NULL || decoderconfiguration_size == 0) { | |
| 164 return 0; // Error: input invalid | |
| 165 } | |
| 166 | |
| 167 // We can skip the four first bytes as they're only profile information. | |
| 168 decoder_configuration += 4; | |
| 169 // Fifth byte's two LSBs contain the interleaving field's size minus one | |
| 170 uint8 size_of_len_field = (*decoder_configuration & 0x3) + 1; | |
| 171 if (size_of_len_field != 1 && size_of_len_field != 2 && | |
| 172 size_of_len_field != 4) { | |
| 173 return 0; // Error: invalid input, NAL unit field len is not correct | |
| 174 } | |
| 175 decoder_configuration++; | |
| 176 // Sixth byte's five LSBs contain the number of SPSs | |
| 177 uint8 sps_count = *decoder_configuration & 0x1F; | |
| 178 decoder_configuration++; | |
| 179 // Then we have N * SPS's with two byte length field and actual SPS | |
| 180 while (sps_count-- > 0) { | |
| 181 uint16 sps_len = decoder_configuration[0] << 8 | | |
| 182 decoder_configuration[1]; | |
| 183 decoder_configuration += 2; | |
| 184 if (out_size + 1 + sizeof(kStartCodePrefix) + sps_len > | |
| 185 *output_size) { | |
| 186 *output_size = 0; | |
| 187 return 0; // too small output buffer; | |
| 188 } | |
| 189 // write the SPS to output, always with zero byte + start code prefix | |
| 190 *outscan = 0; // zero byte | |
| 191 outscan += 1; | |
| 192 memcpy(outscan, kStartCodePrefix, sizeof(kStartCodePrefix)); | |
| 193 outscan += sizeof(kStartCodePrefix); | |
| 194 memcpy(outscan, decoder_configuration, sps_len); | |
| 195 decoder_configuration += sps_len; | |
| 196 outscan += sps_len; | |
| 197 out_size += 1 + sizeof(kStartCodePrefix) + sps_len; | |
| 198 } | |
| 199 // Then we have the numner of pps in one byte | |
| 200 uint8 pps_count = *decoder_configuration; | |
| 201 decoder_configuration++; | |
| 202 // And finally, we have N * PPS with two byte length field and actual PPS | |
| 203 while (pps_count-- > 0) { | |
| 204 uint16 pps_len = decoder_configuration[0] << 8 | decoder_configuration[1]; | |
| 205 decoder_configuration += 2; | |
| 206 if (out_size + 1 + sizeof(kStartCodePrefix) + pps_len > | |
| 207 *output_size) { | |
| 208 *output_size = 0; | |
| 209 return 0; // too small output buffer; | |
| 210 } | |
| 211 // write the SPS to output, always with zero byte + start code prefix | |
| 212 *outscan = 0; // zero byte | |
| 213 outscan += 1; | |
| 214 memcpy(outscan, kStartCodePrefix, sizeof(kStartCodePrefix)); | |
| 215 outscan += sizeof(kStartCodePrefix); | |
| 216 memcpy(outscan, decoder_configuration, pps_len); | |
| 217 decoder_configuration += pps_len; | |
| 218 outscan += pps_len; | |
| 219 out_size += 1 + sizeof(kStartCodePrefix) + pps_len; | |
| 220 } | |
| 221 // We're done processing the AVCDecoderConfigurationRecord, store the needed | |
| 222 // information | |
| 223 nal_unit_length_field_width_ = size_of_len_field; | |
| 224 configuration_processed_ = true; | |
| 225 *output_size = out_size; | |
| 226 return true; | |
| 227 } | |
| 228 | |
| 229 bool H264BitstreamConverter::ConvertNalUnitStreamToByteStream( | |
| 230 const uint8* input, uint32 input_size, | |
| 231 uint8* output, uint32* output_size) { | |
| 232 const uint8* inscan = input; // We read the input from here progressively | |
| 233 uint8* outscan = output; // We write the output to here progressively | |
| 234 uint32 data_left = input_size; | |
| 235 | |
| 236 if (inscan == NULL || input_size == 0 || | |
| 237 outscan == NULL || *output_size == 0) { | |
| 238 *output_size = 0; | |
| 239 return false; // Error: invalid input | |
| 240 } | |
| 241 | |
| 242 // NAL unit width should be known at this point | |
| 243 CHECK(nal_unit_length_field_width_ == 1 || | |
| 244 nal_unit_length_field_width_ == 2 || | |
| 245 nal_unit_length_field_width_ == 4); | |
| 246 | |
| 247 // Do the actual conversion for the actual input packet | |
| 248 while (data_left > 0) { | |
| 249 uint8 i; | |
| 250 uint32 nal_unit_length; | |
| 251 | |
| 252 // Read the next NAL unit length from the input buffer by scanning | |
| 253 // the input stream with the specific length field width | |
| 254 for (nal_unit_length = 0, i = nal_unit_length_field_width_; | |
| 255 i > 0 && data_left > 0; | |
| 256 inscan++, i--, data_left--) { | |
| 257 nal_unit_length <<= 8; | |
| 258 nal_unit_length |= *inscan; | |
| 259 } | |
| 260 | |
| 261 if (nal_unit_length == 0) { | |
| 262 break; // Successful conversion, end of buffer | |
| 263 } else if (nal_unit_length > data_left) { | |
| 264 *output_size = 0; | |
| 265 return false; // Error: not enough data for correct conversion | |
| 266 } | |
| 267 | |
| 268 uint32 start_code_len; | |
| 269 first_nal_unit_in_access_unit_ ? | |
| 270 start_code_len = sizeof(kStartCodePrefix) + 1 : | |
| 271 start_code_len = sizeof(kStartCodePrefix); | |
| 272 if (static_cast<uint32>(outscan - output) + | |
| 273 start_code_len + nal_unit_length > *output_size) { | |
| 274 *output_size = 0; | |
| 275 return false; // Error: too small output buffer | |
| 276 } | |
| 277 | |
| 278 // Five least significant bits of first NAL unit byte signify | |
| 279 // nal_unit_type. | |
| 280 int nal_unit_type = *inscan & 0x1F; | |
| 281 | |
| 282 // Check if this packet marks access unit boundary by checking the | |
| 283 // packet type. | |
| 284 if (IsAccessUnitBoundaryNal(nal_unit_type)) { | |
| 285 first_nal_unit_in_access_unit_ = true; | |
| 286 } | |
| 287 | |
| 288 // Write extra zero-byte before start code prefix if this packet | |
| 289 // signals next access unit. | |
| 290 if (first_nal_unit_in_access_unit_) { | |
| 291 *outscan = 0; | |
| 292 outscan++; | |
| 293 first_nal_unit_in_access_unit_ = false; | |
| 294 } | |
| 295 | |
| 296 // No need to write leading zero bits. | |
| 297 // Write start-code prefix. | |
| 298 memcpy(outscan, kStartCodePrefix, sizeof(kStartCodePrefix)); | |
| 299 outscan += sizeof(kStartCodePrefix); | |
| 300 // Then write the actual NAL unit from the input buffer. | |
| 301 memcpy(outscan, inscan, nal_unit_length); | |
| 302 inscan += nal_unit_length; | |
| 303 data_left -= nal_unit_length; | |
| 304 outscan += nal_unit_length; | |
| 305 // No need for trailing zero bits. | |
| 306 } | |
| 307 // Successful conversion, output the freshly allocated bitstream buffer. | |
| 308 *output_size = static_cast<uint32>(outscan - output); | |
| 309 return true; | |
| 310 } | |
| 311 | |
| 312 } // namespace media | |
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Chromium Code Reviews
Issue 10690140:
Reorganize bitstream converter classes. (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src