mpegts.js/src/demux/h264.ts

HTML5 MPEG2-TS Stream Player

import Log from "../utils/logger";

export enum H264NaluType {
    kUnspecified = 0,
    kSliceNonIDR,
    kSliceDPA,
    kSliceDPB,
    kSliceDPC,
    kSliceIDR,
    kSliceSEI,
    kSliceSPS,
    kSlicePPS,
    kSliceAUD,
    kEndOfSequence,
    kEndOfStream,
    kFiller,
    kSPSExt,
    kReserved0
}

export class H264NaluPayload {
    type: H264NaluType;
    data: Uint8Array;
}

export class H264NaluAVC1 {
    type: H264NaluType;
    data: Uint8Array;

    constructor(nalu: H264NaluPayload) {
        let nalu_size = nalu.data.byteLength;

        this.type = nalu.type;
        this.data = new Uint8Array(4 + nalu_size);  // 4 byte length-header + nalu payload

        let v = new DataView(this.data.buffer);
        // Fill 4 byte length-header
        v.setUint32(0, nalu_size);
        // Copy payload
        this.data.set(nalu.data, 4);
    }
}

export class H264AnnexBParser {

    private readonly TAG: string = "H264AnnexBParser";

    private data_: Uint8Array;
    private current_startcode_offset_: number = 0;
    private eof_flag_: boolean = false;

    public constructor(data: Uint8Array) {
        this.data_ = data;
        this.current_startcode_offset_ = this.findNextStartCodeOffset(0);
        if (this.eof_flag_) {
            Log.e(this.TAG, "Could not find H264 startcode until payload end!");
        }
    }

    private findNextStartCodeOffset(start_offset: number) {
        let i = start_offset;
        let data = this.data_;

        while (true) {
            if (i + 3 >= data.byteLength) {
                this.eof_flag_ = true;
                return data.byteLength;
            }

            // search 00 00 00 01 or 00 00 01
            let uint32 = (data[i + 0] << 24)
                        | (data[i + 1] << 16)
                        | (data[i + 2] << 8)
                        | (data[i + 3]);
            let uint24 = (data[i + 0] << 16)
                        | (data[i + 1] << 8)
                        | (data[i + 2]);
            if (uint32 === 0x00000001 || uint24 === 0x000001) {
                return i;
            } else {
                i++;
            }
        }
    }

    public readNextNaluPayload(): H264NaluPayload | null {
        let data = this.data_;
        let nalu_payload: H264NaluPayload = null;

        while (nalu_payload == null) {
            if (this.eof_flag_) {
                break;
            }
            // offset pointed to start code
            let startcode_offset = this.current_startcode_offset_;

            // nalu payload start offset
            let offset = startcode_offset;
            let u32 = (data[offset] << 24) | (data[offset + 1] << 16) | (data[offset + 2] << 8) | (data[offset + 3]);
            if (u32 === 0x00000001) {
                offset += 4;
            } else {
                offset += 3;
            }

            let nalu_type: H264NaluType = data[offset] & 0x1F;
            let forbidden_bit = (data[offset] & 0x80) >>> 7;

            let next_startcode_offset = this.findNextStartCodeOffset(offset);
            this.current_startcode_offset_ = next_startcode_offset;

            if (nalu_type >= H264NaluType.kReserved0) {
                continue;
            }
            if (forbidden_bit !== 0) {
                // Log.e(this.TAG, `forbidden_bit near offset ${offset} should be 0 but has value ${forbidden_bit}`);
                continue;
            }

            let payload_data = data.subarray(offset, next_startcode_offset);

            nalu_payload = new H264NaluPayload();
            nalu_payload.type = nalu_type;
            nalu_payload.data = payload_data;
        }

        return nalu_payload;
    }

}


export class AVCDecoderConfigurationRecord {

    private data: Uint8Array;

    // sps, pps: require Nalu without 4 byte length-header
    public constructor(sps: Uint8Array, pps: Uint8Array, sps_details: any) {
        let length = 6 + 2 + sps.byteLength + 1 + 2 + pps.byteLength;
        let need_extra_fields = false;

        if (sps[3] !== 66 && sps[3] !== 77 && sps[3] !== 88) {
            need_extra_fields = true;
            length += 4;
        }

        let data = this.data = new Uint8Array(length);

        data[0] = 0x01;    // configurationVersion
        data[1] = sps[1];  // AVCProfileIndication
        data[2] = sps[2];  // profile_compatibility
        data[3] = sps[3];  // AVCLevelIndication
        data[4] = 0xFF;    // 111111 + lengthSizeMinusOne(3)

        data[5] = 0xE0 | 0x01  // 111 + numOfSequenceParameterSets

        let sps_length = sps.byteLength;
        data[6] = sps_length >>> 8;  // sequenceParameterSetLength
        data[7] = sps_length & 0xFF;

        let offset = 8;
        data.set(sps, 8);
        offset += sps_length;

        data[offset] = 1;  // numOfPictureParameterSets

        let pps_length = pps.byteLength;
        data[offset + 1] = pps_length >>> 8;  // pictureParameterSetLength
        data[offset + 2] = pps_length & 0xFF;

        data.set(pps, offset + 3);
        offset += 3 + pps_length;

        if (need_extra_fields) {
            data[offset] = 0xFC | sps_details.chroma_format_idc;
            data[offset + 1] = 0xF8 | (sps_details.bit_depth_luma - 8);
            data[offset + 2] = 0xF8 | (sps_details.bit_depth_chroma - 8);
            data[offset + 3] = 0x00;  // number of sps ext
            offset += 4;
        }
    }

    public getData() {
        return this.data;
    }

}