78 lines
2.2 KiB
C
78 lines
2.2 KiB
C
/*
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* Frontend Status Monitor plugin for the Video Disk Recorder
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*
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* See the README file for copyright information and how to reach the author.
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*
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*/
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#include "femontools.h"
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#include "femonaac.h"
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#define IS_HEAAC_AUDIO(buf) (((buf)[0] == 0xFF) && (((buf)[1] & 0xF6) == 0xF0))
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static unsigned int samplerates[16] =
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{
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96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050, 16000, 12000, 11025, 8000, -1, -1, -1, -1
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};
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bool getAACAudioInfo(uint8_t *buf, int len, audio_info_t *info)
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{
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// HE-AAC audio detection, search for syncword with layer set to 0
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if ((len < 4) || !IS_HEAAC_AUDIO(buf))
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return false;
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/* ADTS Fixed Header:
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* syncword 12b always: '111111111111'
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* id 1b 0: MPEG-4, 1: MPEG-2
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* layer 2b always: '00'
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* protection_absent 1b
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* profile 2b 0: Main profile AAC MAIN 1: Low Complexity profile (LC) AAC LC 2: Scalable Sample Rate profile (SSR) AAC SSR 3: (reserved) AAC LTP
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* sampling_frequency_index 4b
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* private_bit 1b
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* channel_configuration 3b
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* original/copy 1b
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* home 1b
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* emphasis 2b only if ID == 0 (ie MPEG-4)
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*/
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int sampling_frequency_index = (buf[2] & 0x03C) >> 2;
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int channel_configuration = ((buf[2] & 0x01) << 2) | ((buf[3] & 0xC0) >> 6);
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info->codec = AUDIO_CODEC_HEAAC;
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info->bitrate = AUDIO_BITRATE_RESERVED;
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switch (channel_configuration) {
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case 0:
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info->channelMode = AUDIO_CHANNEL_MODE_STEREO;
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break;
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case 1:
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info->channelMode = AUDIO_CHANNEL_MODE_JOINT_STEREO;
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break;
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case 2:
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info->channelMode = AUDIO_CHANNEL_MODE_DUAL;
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break;
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case 3:
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info->channelMode = AUDIO_CHANNEL_MODE_SINGLE;
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break;
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default:
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info->channelMode = AUDIO_CHANNEL_MODE_INVALID;
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break;
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}
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switch (sampling_frequency_index) {
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case 0xC ... 0xF:
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info->samplingFrequency = AUDIO_SAMPLING_FREQUENCY_RESERVED;
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break;
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default:
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info->samplingFrequency = samplerates[sampling_frequency_index];
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break;
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}
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return true;
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}
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