shaka-player
Version:
DASH/EME video player library
325 lines (289 loc) • 9.5 kB
JavaScript
/*! @license
* Shaka Player
* Copyright 2016 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
goog.provide('shaka.transmuxer.H264');
goog.require('shaka.util.ExpGolomb');
goog.require('shaka.util.Uint8ArrayUtils');
/**
* H.264 utils
*/
shaka.transmuxer.H264 = class {
/**
* Read a sequence parameter set and return some interesting video
* properties. A sequence parameter set is the H264 metadata that
* describes the properties of upcoming video frames.
*
* @param {!Array.<shaka.extern.VideoNalu>} nalus
* @return {?{height: number, width: number, videoConfig: !Uint8Array}}
*/
static parseInfo(nalus) {
const H264 = shaka.transmuxer.H264;
if (!nalus.length) {
return null;
}
const spsNalu = nalus.find((nalu) => {
return nalu.type == H264.NALU_TYPE_SPS_;
});
const ppsNalu = nalus.find((nalu) => {
return nalu.type == H264.NALU_TYPE_PPS_;
});
if (!spsNalu || !ppsNalu) {
return null;
}
const expGolombDecoder = new shaka.util.ExpGolomb(spsNalu.data);
// profile_idc
const profileIdc = expGolombDecoder.readUnsignedByte();
// constraint_set[0-5]_flag
expGolombDecoder.readUnsignedByte();
// level_idc u(8)
expGolombDecoder.readUnsignedByte();
// seq_parameter_set_id
expGolombDecoder.skipExpGolomb();
// some profiles have more optional data we don't need
if (H264.PROFILES_WITH_OPTIONAL_SPS_DATA_.includes(profileIdc)) {
const chromaFormatIdc = expGolombDecoder.readUnsignedExpGolomb();
if (chromaFormatIdc === 3) {
// separate_colour_plane_flag
expGolombDecoder.skipBits(1);
}
// bit_depth_luma_minus8
expGolombDecoder.skipExpGolomb();
// bit_depth_chroma_minus8
expGolombDecoder.skipExpGolomb();
// qpprime_y_zero_transform_bypass_flag
expGolombDecoder.skipBits(1);
// seq_scaling_matrix_present_flag
if (expGolombDecoder.readBoolean()) {
const scalingListCount = (chromaFormatIdc !== 3) ? 8 : 12;
for (let i = 0; i < scalingListCount; i++) {
// seq_scaling_list_present_flag[ i ]
if (expGolombDecoder.readBoolean()) {
if (i < 6) {
expGolombDecoder.skipScalingList(16);
} else {
expGolombDecoder.skipScalingList(64);
}
}
}
}
}
// log2_max_frame_num_minus4
expGolombDecoder.skipExpGolomb();
const picOrderCntType = expGolombDecoder.readUnsignedExpGolomb();
if (picOrderCntType === 0) {
// log2_max_pic_order_cnt_lsb_minus4
expGolombDecoder.readUnsignedExpGolomb();
} else if (picOrderCntType === 1) {
// delta_pic_order_always_zero_flag
expGolombDecoder.skipBits(1);
// offset_for_non_ref_pic
expGolombDecoder.skipExpGolomb();
// offset_for_top_to_bottom_field
expGolombDecoder.skipExpGolomb();
const numRefFramesInPicOrderCntCycle =
expGolombDecoder.readUnsignedExpGolomb();
for (let i = 0; i < numRefFramesInPicOrderCntCycle; i++) {
// offset_for_ref_frame[ i ]
expGolombDecoder.skipExpGolomb();
}
}
// max_num_ref_frames
expGolombDecoder.skipExpGolomb();
// gaps_in_frame_num_value_allowed_flag
expGolombDecoder.skipBits(1);
const picWidthInMbsMinus1 =
expGolombDecoder.readUnsignedExpGolomb();
const picHeightInMapUnitsMinus1 =
expGolombDecoder.readUnsignedExpGolomb();
const frameMbsOnlyFlag = expGolombDecoder.readBits(1);
if (frameMbsOnlyFlag === 0) {
// mb_adaptive_frame_field_flag
expGolombDecoder.skipBits(1);
}
// direct_8x8_inference_flag
expGolombDecoder.skipBits(1);
let frameCropLeftOffset = 0;
let frameCropRightOffset = 0;
let frameCropTopOffset = 0;
let frameCropBottomOffset = 0;
// frame_cropping_flag
if (expGolombDecoder.readBoolean()) {
frameCropLeftOffset = expGolombDecoder.readUnsignedExpGolomb();
frameCropRightOffset = expGolombDecoder.readUnsignedExpGolomb();
frameCropTopOffset = expGolombDecoder.readUnsignedExpGolomb();
frameCropBottomOffset = expGolombDecoder.readUnsignedExpGolomb();
}
const height = ((2 - frameMbsOnlyFlag) *
(picHeightInMapUnitsMinus1 + 1) * 16) - (frameCropTopOffset * 2) -
(frameCropBottomOffset * 2);
const width = ((picWidthInMbsMinus1 + 1) * 16) -
frameCropLeftOffset * 2 - frameCropRightOffset * 2;
// assemble the SPSs
let sps = [];
const spsData = spsNalu.fullData;
sps.push((spsData.byteLength >>> 8) & 0xff);
sps.push(spsData.byteLength & 0xff);
sps = sps.concat(...spsData);
// assemble the PPSs
let pps = [];
const ppsData = ppsNalu.fullData;
pps.push((ppsData.byteLength >>> 8) & 0xff);
pps.push(ppsData.byteLength & 0xff);
pps = pps.concat(...ppsData);
const videoConfig = new Uint8Array(
[
0x01, // version
sps[3], // profile
sps[4], // profile compat
sps[5], // level
0xfc | 3, // lengthSizeMinusOne, hard-coded to 4 bytes
0xe0 | 1, // 3bit reserved (111) + numOfSequenceParameterSets
].concat(sps).concat([
1, // numOfPictureParameterSets
]).concat(pps));
return {
height,
width,
videoConfig,
};
}
/**
* @param {!Array.<shaka.extern.VideoNalu>} nalus
* @return {?{data: !Uint8Array, isKeyframe: boolean}}
*/
static parseFrame(nalus) {
const H264 = shaka.transmuxer.H264;
let isKeyframe = false;
let data = new Uint8Array([]);
const spsNalu = nalus.find((nalu) => {
return nalu.type == H264.NALU_TYPE_SPS_;
});
let avcSample = false;
for (const nalu of nalus) {
let push = false;
switch (nalu.type) {
case H264.NALU_TYPE_NDR_: {
avcSample = true;
push = true;
const data = nalu.data;
// Only check slice type to detect KF in case SPS found in same packet
// (any keyframe is preceded by SPS ...)
if (spsNalu && data.length > 4) {
// retrieve slice type by parsing beginning of NAL unit (follow
// H264 spec,slice_header definition) to detect keyframe embedded
// in NDR
const sliceType = new shaka.util.ExpGolomb(data).readSliceType();
// 2 : I slice, 4 : SI slice, 7 : I slice, 9: SI slice
// SI slice : A slice that is coded using intra prediction only and
// using quantisation of the prediction samples.
// An SI slice can be coded such that its decoded samples can be
// constructed identically to an SP slice.
// I slice: A slice that is not an SI slice that is decoded using
// intra prediction only.
if (sliceType === 2 || sliceType === 4 ||
sliceType === 7 || sliceType === 9) {
isKeyframe = true;
}
}
break;
}
case H264.NALU_TYPE_IDR_:
avcSample = true;
push = true;
isKeyframe = true;
break;
case H264.NALU_TYPE_SEI_:
push = true;
break;
case H264.NALU_TYPE_SPS_:
push = true;
break;
case H264.NALU_TYPE_PPS_:
push = true;
break;
case H264.NALU_TYPE_AUD_:
push = true;
avcSample = true;
break;
case H264.NALU_TYPE_FILLER_DATA_:
push = true;
break;
default:
push = false;
break;
}
if (avcSample && push) {
const size = nalu.fullData.byteLength;
const naluLength = new Uint8Array(4);
naluLength[0] = (size >> 24) & 0xff;
naluLength[1] = (size >> 16) & 0xff;
naluLength[2] = (size >> 8) & 0xff;
naluLength[3] = size & 0xff;
data = shaka.util.Uint8ArrayUtils.concat(
data, naluLength, nalu.fullData);
}
}
if (!data.byteLength) {
return null;
}
return {
data,
isKeyframe,
};
}
};
/**
* NALU type for NDR for H.264.
* @const {number}
* @private
*/
shaka.transmuxer.H264.NALU_TYPE_NDR_ = 0x01;
/**
* NALU type for Instantaneous Decoder Refresh (IDR) for H.264.
* @const {number}
* @private
*/
shaka.transmuxer.H264.NALU_TYPE_IDR_ = 0x05;
/**
* NALU type for Supplemental Enhancement Information (SEI) for H.264.
* @const {number}
* @private
*/
shaka.transmuxer.H264.NALU_TYPE_SEI_ = 0x06;
/**
* NALU type for Sequence Parameter Set (SPS) for H.264.
* @const {number}
* @private
*/
shaka.transmuxer.H264.NALU_TYPE_SPS_ = 0x07;
/**
* NALU type for Picture Parameter Set (PPS) for H.264.
* @const {number}
* @private
*/
shaka.transmuxer.H264.NALU_TYPE_PPS_ = 0x08;
/**
* NALU type for Access Unit Delimiter (AUD) for H.264.
* @const {number}
* @private
*/
shaka.transmuxer.H264.NALU_TYPE_AUD_ = 0x09;
/**
* NALU type for Filler Data for H.264.
* @const {number}
* @private
*/
shaka.transmuxer.H264.NALU_TYPE_FILLER_DATA_ = 0x0c;
/**
* Values of profile_idc that indicate additional fields are included in the
* SPS.
* see Recommendation ITU-T H.264 (4/2013)
* 7.3.2.1.1 Sequence parameter set data syntax
*
* @const {!Array.<number>}
* @private
*/
shaka.transmuxer.H264.PROFILES_WITH_OPTIONAL_SPS_DATA_ =
[100, 110, 122, 244, 44, 83, 86, 118, 128, 138, 139, 134];