qiaohaijiao commented on code in PR #1440: URL: https://github.com/apache/nuttx-apps/pull/1440#discussion_r1037793939
########## system/nxplayer/nxplayer_mp3.c: ########## @@ -0,0 +1,321 @@ +/**************************************************************************** + * apps/system/nxplayer/nxplayer_mp3.c + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. The + * ASF licenses this file to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance with the + * License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * 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. + * + ****************************************************************************/ + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <sys/types.h> + +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> + +#include <nuttx/audio/audio.h> + +#include "system/nxplayer.h" + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +#define ID3V2_BIT_MASK 0x7F + +/**************************************************************************** + * Private Type Declarations + ****************************************************************************/ + +const static uint16_t g_mpa_freq_tab[3] = +{ + 44100, 48000, 32000 +}; + +const static uint16_t g_mpa_bitrate_tab[2][3][15] = +{ + { + { + 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448 + }, + { + 0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384 + }, + { + 0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 + } + }, + { + { + 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256 + }, + { + 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 + }, + { + 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 + } + } +}; + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +static int nxplayer_check_mpeg(uint32_t header) +{ + int ret = -EINVAL; + + /* header */ + + if ((header & 0xffe00000) != 0xffe00000) + { + return ret; + } + + /* version check */ + + if ((header & (3 << 19)) == 1 << 19) + { + return ret; + } + + /* layer check */ + + if ((header & (3 << 17)) == 0) + { + return ret; + } + + /* bit rate */ + + if ((header & (0xf << 12)) == 0xf << 12) + { + return ret; + } + + /* frequency */ + + if ((header & (3 << 10)) == 3 << 10) + { + return ret; + } + + return 0; +} + +static int nxplayer_parse_mpeg(uint32_t header, FAR uint32_t *samplerate, + FAR uint8_t *chans, FAR uint8_t *bps) +{ + int sample_rate; + int frame_size; + int padding; + int mpeg25; + int sr_idx; + int br_idx; + int layer; + int mode; + int lsf; + int ret; + + ret = nxplayer_check_mpeg(header); + if (ret < 0) + { + return ret; + } + + if (header & (1 << 20)) + { + lsf = (header & (1 << 19)) ? 0 : 1; + mpeg25 = 0; + } + else + { + lsf = 1; + mpeg25 = 1; + } + + layer = 4 - ((header >> 17) & 3); + br_idx = (header >> 12) & 0xf; + sr_idx = (header >> 10) & 3; + padding = (header >> 9) & 1; + mode = (header >> 6) & 3; + + if (sr_idx >= sizeof(g_mpa_freq_tab) / sizeof(g_mpa_freq_tab[0]) || + br_idx >= 0xf) + { + return -EINVAL; + } + + sample_rate = g_mpa_freq_tab[sr_idx] >> (lsf + mpeg25); + + if (br_idx != 0) + { + frame_size = g_mpa_bitrate_tab[lsf][layer - 1][br_idx]; + + switch (layer) + { + case 1: + frame_size = (frame_size * 12000) / sample_rate; + frame_size = (frame_size + padding) * 4; + break; + + case 2: + frame_size = (frame_size * 144000) / sample_rate; + frame_size += padding; + break; + + default: + case 3: + frame_size = (frame_size * 144000) / (sample_rate << lsf); + frame_size += padding; + break; + } + } + else + { + /* if no frame size computed, signal it */ + + return -EINVAL; + } + + if (samplerate) + { + *samplerate = sample_rate; + } + + if (chans) + { + *chans = mode == 3 ? 1 : 2; + } + + if (bps) + { + *bps = 16; + } + + return frame_size; +} + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: nxplayer_parse_mp3 + * + * nxplayer_parse_mp3() parse mp3 header, get samplerate, channels, bps. + * + ****************************************************************************/ + +int nxplayer_parse_mp3(int fd, FAR uint32_t *samplerate, + FAR uint8_t *chans, FAR uint8_t *bps) +{ + uint32_t mpa_header; + uint8_t buffer[10]; + off_t position; + int ret; + + if (fd == -1) + { + return -EINVAL; + } + + read(fd, buffer, sizeof(buffer)); + position = (buffer[6] & ID3V2_BIT_MASK) * 0x200000 + + (buffer[7] & ID3V2_BIT_MASK) * 0x4000 + + (buffer[8] & ID3V2_BIT_MASK) * 0x80 + + (buffer[9] & ID3V2_BIT_MASK) + + sizeof(buffer); + + lseek(fd, position, SEEK_SET); + + read(fd, buffer, 4); + mpa_header = buffer[0] << 24 | + buffer[1] << 16 | + buffer[2] << 8 | + buffer[3]; + + ret = nxplayer_parse_mpeg(mpa_header, samplerate, chans, bps); + if (ret < 0) + { + return ret; + } + + lseek(fd, position, SEEK_SET); + return OK; +} + +/**************************************************************************** + * Name: nxplayer_fill_mp3 + * + * nxplayer_fill_mp3 fill mp3 data into apb buffer. + * + ****************************************************************************/ + +int nxplayer_fill_mp3(int fd, FAR struct ap_buffer_s *apb) +{ + uint32_t mpa_header; + uint8_t header[16]; + int h_size; + int b_size; + off_t pos; + int size; + int ret; + + if (fd == -1) + { + return -EINVAL; + } + + h_size = 4; Review Comment: done -- This is an automated message from the Apache Git Service. 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