如何将 SCTE35 提示标记从 JSON 转换为二进制？答案

【问题标题】：How do I convert SCTE35 cue marker from JSON to binary?如何将 SCTE35 提示标记从 JSON 转换为二进制？
【发布时间】：2021-07-27 14:31:41
【问题描述】：

我正在研究 MPEG DASH，并且有类似这样的 SCTE35 二进制提示事件。

<Event id="6" presentationTime="50726727">
    <scte35:signal>
        <scte35:binary>/DBhAAAAAAAA///wBQb+qM1E7QBLAhdDVUVJSAAArX+fCAgAAAAALLLXnTUCAAIXQ1VFSUgAACZ/nwgIAAAAACyy150RAAACF0NVRUlIAAAnf58ICAAAAAAsstezEAAAihiGnw==</scte35:binary>
    </scte35:signal>
</Event>

如果使用https://openidconnectweb.azurewebsites.net/Cue?cue=/DBhAAAAAAAA///wBQb+qM1E7QBLAhdDVUVJSAAArX+fCAgAAAAALLLXnTUCAAIXQ1VFSUgAACZ/nwgIAAAAACyy150RAAACF0NVRUlIAAAnf58ICAAAAAAsstezEAAAihiGnw== 解码，它会返回一个 SpliceInfoSection JSON 对象。我希望能够对 JSON 进行更改并将其转换回二进制格式以进行测试。

任何帮助将不胜感激。

【问题讨论】：

标签： json binary mpeg-dash scte-35

【解决方案1】：

三五是最简单的方法。

a@fumatica:~/threefive$ pypy3
Python 3.7.10 (7.3.5+dfsg-2, Jun 03 2021, 20:39:46)
[PyPy 7.3.5 with GCC 10.2.1 20210110] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>> import threefive
>>>> Base64 = "/DAvAAAAAAAA///wFAVIAACPf+/+c2nALv4AUsz1AAAAAAAKAAhDVUVJAAABNWLbowo="
>>>> cue = threefive.Cue(Base64)
>>>> cue.decode()
True
>>>> cue.command
{'calculated_length': 20, 'command_type': 5, 'name': 'Splice Insert', 
'time_specified_flag': True, 'pts_time': 21514.559089, 'break_auto_return':True, 
'break_duration': 60.293567, 'splice_event_id': 1207959695, 'splice_event_cancel_indicator': False, 'out_of_network_indicator': True, 
'program_splice_flag': True, 'duration_flag': True, 'splice_immediate_flag': False, 'component_count': None, 'components': None, 'unique_program_id': 0, 
'avail_num': 0, 'avail_expected': 0}


# Access vars with dot notation

>>>> cue.command.break_duration= 90.0

# re-encode

>>>> cue.encode()
'/DAvAAAAAAAA///wFAVIAACPf+/+c2nALv4Ae5igAAAAAAAKAAhDVUVJAAABNVB2fJs='
>>>> 
>>>> cue.show()
{
    "info_section": {
        "table_id": "0xfc",
        "section_syntax_indicator": false,
        "private": false,
        "sap_type": "0x3",
        "sap_details": "No Sap Type",
        "section_length": 47,
        "protocol_version": 0,
        "encrypted_packet": false,
        "encryption_algorithm": 0,
        "pts_adjustment": 0.0,
        "cw_index": "0xff",
        "tier": "0xfff",
        "splice_command_length": 20,
        "splice_command_type": 5,
        "descriptor_loop_length": 10,
        "crc": "0x62dba30a"
    },
    "command": {
        "calculated_length": 20,
        "command_type": 5,
        "name": "Splice Insert",
        "time_specified_flag": true,
        "pts_time": 21514.559089,
        "break_auto_return": true,
        "break_duration": 90.0,
        "splice_event_id": 1207959695,
        "splice_event_cancel_indicator": false,
        "out_of_network_indicator": true,
        "program_splice_flag": true,
        "duration_flag": true,
        "splice_immediate_flag": false,
        "unique_program_id": 0,
        "avail_num": 0,
        "avail_expected": 0
    },
    "descriptors": [
        {
            "tag": 0,
            "descriptor_length": 8,
            "name": "Avail Descriptor",
            "identifier": "CUEI",
            "provider_avail_id": 309
        }
    ]
}

https://github.com/futzu/scte35-threefive/blob/master/Encoding.md

【讨论】：