[FFmpeg-devel] Re: [PATCH] lavf/whip: improve RTP muxer error message

[Jack Lau via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

> On Feb 11, 2026, at 15:04, Devraj Ajmera via ffmpeg-devel <ffmpeg-devel@ffmpeg.org> wrote:
> 
> Hi Jack,
> 
> Just a gentle ping on the updated patch that replaces the RTP muxer
> error handling with av_unreachable(), incorporating your feedback
> about the reason string and indentation.
> 
> Please let me know if anything else is needed.
> 
> Thanks,
> Devraj
> From 3e5c30b79397cade6b05693c88fd6ab4dc397f33 Mon Sep 17 00:00:00 2001
> From: devraj ajmera <devrajajmera077@gmail.com>
> Date: Fri, 30 Jan 2026 10:06:27 +0530
> Subject: [PATCH] lavf/whip: mark RTP muxer lookup as unreachable
> 
> ---
>  libavformat/whip.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/libavformat/whip.c b/libavformat/whip.c
> index c3507405fa..7f43dbf1a7 100644
> --- a/libavformat/whip.c
> +++ b/libavformat/whip.c
> @@ -1548,12 +1548,10 @@ static int create_rtp_muxer(AVFormatContext *s)
>      WHIPContext *whip = s->priv_data;
>      whip->udp->flags |= AVIO_FLAG_NONBLOCK;
>  
> -    const AVOutputFormat *rtp_format = av_guess_format("rtp", NULL, NULL);
> -    if (!rtp_format) {
> -        av_log(whip, AV_LOG_ERROR,"Failed to guess RTP muxer, ensure RTP is enabled in build\n");
> -        ret = AVERROR(ENOSYS);
> -        goto end;
> -    }
> +   const AVOutputFormat *rtp_format = av_guess_format("rtp", NULL, NULL);

It seems there’re still wrong indentation

And I found some muxers have same issues as whip

So I submit them to https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21731

Waiting other developers comments

> +       if (!rtp_format) {
> +           av_unreachable("RTP muxer should be enabled");
> +        }
>  
>      /* The UDP buffer size, may greater than MTU. */
>      buffer_size = MAX_UDP_BUFFER_SIZE;
> -- 
> 2.52.0.windows.1
> 


> 
> 
> On Fri, Jan 30, 2026 at 5:35 PM Devraj Ajmera <devrajajmera077@gmail.com>
> wrote:
> 
>>> I think the av_unreachable() should be used with a reason
>>> 
>>> So maybe av_unreachable("RTP muxer should be enabled");
>>> 
>>> BTW, it seems you use wrong indent here.
>> 
>> Thanks for the suggestion.
>> 
>> I have updated the code to use av_unreachable() with an explicit
>> reason string, and fixed the indentation to match the existing
>> FFmpeg style.
>> 
>> An updated patch reflecting these changes has been generated
>> and sent.
>> 
>> Regards,
>> Devraj
>> 
>> On Fri, Jan 30, 2026 at 11:02 AM Devraj Ajmera <devrajajmera077@gmail.com>
>> wrote:
>> 
>>>> configure already deps the rtp_muxer via whip_muxer_select, so it
>>> should never hit this error.
>>> 
>>>> So maybe use av_unreachable() to replace current error handling?
>>> 
>>> That makes sense. Since configure already enforces the RTP dependency via
>>> whip_muxer_select, this code path should indeed be unreachable at runtime.
>>> 
>>> I have updated the code to replace the current error handling with
>>> av_unreachable() accordingly, and will send an updated patch reflecting
>>> this change.
>>> 
>>> Regards,
>>> Devraj
>>> 
>>> On Sat, Jan 24, 2026 at 9:04 PM Devraj Ajmera <devrajajmera077@gmail.com>
>>> wrote:
>>> 
>>>> Hi Jack,
>>>> 
>>>>> configure already deps the rtp_muxer via whip_muxer_select, so it
>>>> should never hit this error.
>>>>> So maybe use av_unreachable() to replace current error handling?
>>>> 
>>>> That makes sense. If configure already enforces the RTP dependency via
>>>> whip_muxer_select, then this code path should indeed be unreachable.
>>>> 
>>>> Using av_unreachable() here sounds reasonable. I will prepare an updated
>>>> patch replacing the current error handling accordingly.
>>>> 
>>>> Noted.
>>>> 
>>>> Regards,
>>>> Devraj
>>>> 
>>>> On Fri, Jan 23, 2026 at 12:01 PM Devraj Ajmera <
>>>> devrajajmera077@gmail.com> wrote:
>>>> 
>>>>> Hi Timo,
>>>>> 
>>>>> Thanks for the insightful comment.
>>>>> 
>>>>> You are right that if WHIP hard-depends on RTP, this might be better
>>>>> handled at configure time rather than at runtime. The intent of this
>>>>> patch was limited to improving the clarity of the existing error path,
>>>>> without changing behavior.
>>>>> 
>>>>> I agree this deserves a closer look. Would you prefer addressing this
>>>>> by tightening the configure dependencies for the WHIP muxer, or by
>>>>> adjusting the error handling (e.g. AVERROR_BUG) in this code path?
>>>>> 
>>>>> Thanks,
>>>>> Devraj
>>>>> 
>>>>> On Fri, Jan 23, 2026 at 11:42 AM Devraj Ajmera <
>>>>> devrajajmera077@gmail.com> wrote:
>>>>> 
>>>>>> Hi Jack,
>>>>>> 
>>>>>> Thanks for the review.
>>>>>> 
>>>>>> You are right, the "WHIP:" prefix is unnecessary since av_log already
>>>>>> has context.
>>>>>> I have updated the patch accordingly and sent a revised version.
>>>>>> 
>>>>>> Regards,
>>>>>> Devraj Ajmera
>>>>>> 
>>>>>> On Tue, Jan 20, 2026 at 5:15 PM Devraj Ajmera <
>>>>>> devrajajmera077@gmail.com> wrote:
>>>>>> 
>>>>>>> Hello,
>>>>>>> 
>>>>>>> This patch improves the error message shown when the RTP muxer
>>>>>>> cannot be guessed in the WHIP muxer, making the failure reason
>>>>>>> clearer to users.
>>>>>>> 
>>>>>>> Regards,
>>>>>>> Devraj Ajmera
>>>>>>> 
>>>>>> 
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