fix bug: loop transcoding #3516

[duiniuluantanqin]

What issue has been resolved?

for issue: #3516 #4055 #3618

What is the root cause of the problem?

The issue arises from a mismatch between the input and output formats within the SrsEncoder::initialize_ffmpeg function.

For example:
Input: rtmp://127.0.0.1:1935/live?vhost=__defaultVhost__/livestream_ff
Output: rtmp://127.0.0.1:1935/live/livestream_ff?vhost=__defaultVhost__

This may result in the failure of the code segment responsible for determining whether to loop.

What is the approach to solving this issue?

It simply involves modifying the order of stream and vhost.

How was the issue introduced?

The commit introducing this bug is: 7d47017
The order of parameters in the configuration file has been modified to address the ingest issue.

Outstanding issues

Please note that this PR does not entirely resolve the issue; for example, modifying the output format in configuration still results in exceptions. To comprehensively address this problem, extensive code modifications would be required.

However, strictly adhering to the configuration file format can effectively prevent this issue.

[Copilot]

Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

trunk/src/app/srs_app_encoder.cpp:243

• Passing req->vhost twice may be unintentional. Please verify the parameter order for srs_generate_rtmp_url to ensure that all components of the URL are correct.

std::string input = srs_generate_rtmp_url(SRS_CONSTS_LOCALHOST, req->port, req->vhost, req->vhost, req->app, req->stream, req->param);

[Copilot]

Pull Request Overview

This PR addresses bug #3516 by correcting the RTMP URL formatting in the SrsEncoder::initialize_ffmpeg function.

• Replaces manual string concatenation with srs_generate_rtmp_url.
• Modifies parameter ordering to address the inversion of 'stream' and 'vhost'.

[Copilot]

The function call to srs_generate_rtmp_url explicitly passes 'req->vhost' twice; please verify that the parameter order is correct to ensure the URL is generated with 'stream' and 'vhost' in the intended positions.

Suggested change

	std::string input = srs_generate_rtmp_url(SRS_CONSTS_LOCALHOST, req->port, req->vhost, req->vhost, req->app, req->stream, req->param);
	std::string input = srs_generate_rtmp_url(SRS_CONSTS_LOCALHOST, req->port, req->vhost, req->stream, req->app, req->stream, req->param);

[duiniuluantanqin]

Not accepted.

[suzp1984]

Is this patch really fix the bug?
The bug said the transcode stream can't output to same srs instance with same vhost.
output rtmp://127.0.0.1:[port]/[app]/[stream]_[engine]?vhost=[vhost];
It seems this PR didn't improve anything.

[duiniuluantanqin]

The root cause of the issue lies in the order of the vhosts, which leads this segment of code to fail; therefore, merely rearranging the order resolves the problem.

[duiniuluantanqin]

I've revised the code, which should render it more comprehensible.

[Copilot]

Pull Request Overview

This PR reorders the URL parameter placement in the encoder initialization to resolve bugs related to parameter mismatches.

• Reorders the placement of the "vhost" parameter from before the stream to after the stream.
• Aims to fix looping issues by aligning the input and output URL formats.

Comments suppressed due to low confidence (1)

trunk/src/app/srs_app_encoder.cpp:252

• The reordering of the URL parameters appears to address the reported issue, but please verify that the new sequence handles edge cases such as streams with existing query parameters; consider adding unit tests to ensure robustness.

input += "?vhost=";