98 lines
2.6 KiB
C
98 lines
2.6 KiB
C
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Vidtv serves as a reference DVB driver and helps validate the existing APIs
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* in the media subsystem. It can also aid developers working on userspace
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* applications.
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*
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* This file contains the code for an AES3 (also known as AES/EBU) encoder.
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* It is based on EBU Tech 3250 and SMPTE 302M technical documents.
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*
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* This encoder currently supports 16bit AES3 subframes using 16bit signed
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* integers.
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*
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* Note: AU stands for Access Unit, and AAU stands for Audio Access Unit
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*
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* Copyright (C) 2020 Daniel W. S. Almeida
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*/
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#ifndef VIDTV_S302M_H
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#define VIDTV_S302M_H
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#include <linux/types.h>
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#include "vidtv_encoder.h"
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/* see SMPTE 302M 2007 clause 7.3 */
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#define VIDTV_S302M_BUF_SZ 65024
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/* see ETSI TS 102 154 v.1.2.1 clause 7.3.5 */
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#define VIDTV_S302M_FORMAT_IDENTIFIER 0x42535344
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/**
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* struct vidtv_s302m_ctx - s302m encoder context.
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* @enc: A pointer to the containing encoder structure.
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* @frame_index: The current frame in a block
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* @au_count: The total number of access units encoded up to now
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* @last_duration: Duration of the tone currently being played
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* @note_offset: Position at the music tone array
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* @last_tone: Tone currently being played
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*/
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struct vidtv_s302m_ctx {
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struct vidtv_encoder *enc;
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u32 frame_index;
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u32 au_count;
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int last_duration;
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unsigned int note_offset;
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enum musical_notes last_tone;
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};
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/*
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* struct vidtv_smpte_s302m_es - s302m MPEG Elementary Stream header.
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*
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* See SMPTE 302M 2007 table 1.
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*/
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struct vidtv_smpte_s302m_es {
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/*
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*
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* audio_packet_size:16;
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* num_channels:2;
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* channel_identification:8;
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* bits_per_sample:2; // 0x0 for 16bits
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* zero:4;
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*/
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__be32 bitfield;
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} __packed;
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struct vidtv_s302m_frame_16 {
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u8 data[5];
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} __packed;
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/**
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* struct vidtv_s302m_encoder_init_args - Args for the s302m encoder.
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*
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* @name: A name to identify this particular instance
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* @src_buf: The source buffer, encoder will default to a sine wave if this is NULL.
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* @src_buf_sz: The size of the source buffer.
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* @es_pid: The MPEG Elementary Stream PID to use.
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* @sync: Attempt to synchronize audio with this video encoder, if not NULL.
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* @last_sample_cb: A callback called when the encoder runs out of data.
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* @head: Add to this chain
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*/
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struct vidtv_s302m_encoder_init_args {
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char *name;
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void *src_buf;
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u32 src_buf_sz;
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u16 es_pid;
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struct vidtv_encoder *sync;
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void (*last_sample_cb)(u32 sample_no);
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struct vidtv_encoder *head;
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};
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struct vidtv_encoder
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*vidtv_s302m_encoder_init(struct vidtv_s302m_encoder_init_args args);
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void vidtv_s302m_encoder_destroy(struct vidtv_encoder *encoder);
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#endif /* VIDTV_S302M_H */
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