将HEv2 AAC合并到用于HLS内容的MPEG-TS中 [英] Incorporate HEv2 AAC into an MPEG-TS for HLS content

问题描述

我尝试在HLS的MPEG传输流(TS)中找到有关AAC HEv2(PS)的任何信息.

根据解决方案

有两种方法可以将AAC放入传输流中.

1.使用ADTS语法(MPEG2样式).

在这种情况下，应将PMT的stream_type指定为0x0F(具有ADTS传输语法的ISO/IEC 13818-7音频).

因此，您只能使用旧"(MPEG2)AAC版本，而不能使用SBR和PS.

2.使用LATM + LOAS/AudioSyncStream语法(MPEG4样式).

在这种情况下，应将PMT的stream_type指定为0x11(具有LATM传输语法的ISO/IEC 14496-3音频).

您可以使用所有新功能(MPEG4)AAC功能，包括SBR和PS.

此外，DVB标准ETSI TS 101 154要求:HEv1/HEv2 AAC必须使用LATM语法进行传输.

I try to find any info about AAC HEv2 (PS) in an MPEG Transport Stream (TS) for HLS.

According to the HLS Authoring Specification for Apple Devices AAC HEv2 is a supported format. AAC HEv2 is part of MPEG-4, but I cannot understand how HEv2 could fit into a transport stream.

SBR (or HEv1) can be in TS by implicit signaling. In case of MP4 we have an audio specific config. But how can I multiplex AAC Parametric Stereo into the TS?

Is it available or not?
I cannot find any info from the Apple site and so on.

解决方案

There are two ways to put AAC into transport stream.

1. Using ADTS syntax (MPEG2-style).

In a such case PMT's stream_type should be specified as 0x0F (ISO/IEC 13818-7 Audio with ADTS transport syntax).

So, you are limited to using "old" (MPEG2) AAC versions only, without SBR and PS.

2. Using LATM+LOAS/AudioSyncStream syntax (MPEG4-style).

In a such case PMT's stream_type should be specified as 0x11 (ISO/IEC 14496-3 Audio with the LATM transport syntax).

And you can use all the force of "new" (MPEG4) AAC features, including SBR and PS.

Furthermore, DVB standard ETSI TS 101 154 demands: HEv1/HEv2 AAC shall be transmitted using LATM syntax.

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