[FFmpeg-devel] [FFmpeg-cvslog] ffmpeg: add per-stream input option drop_changed

[Gyan Doshi]

On 2025-03-24 06:42 pm, James Almer wrote:
> On 3/24/2025 9:31 AM, Martin Storsjö wrote:
>> On Mon, 24 Mar 2025, Gyan Doshi wrote:
>>
>>> ffmpeg | branch: master | Gyan Doshi <ffmpeg at gyani.pro> | Sat Mar 15 
>>> 16:51:05 2025 +0530| [cbbc927a67f142a02bfc5d047c03587599ee5b55] | 
>>> committer: Gyan Doshi
>>>
>>> ffmpeg: add per-stream input option drop_changed
>>>
>>> This is a replacement in ffmpeg for the deprecated avcodec flag 
>>> AV_CODEC_FLAG_DROPCHANGED.
>>>
>>> This option is meant to be used when the filtergraph should not be
>>> reinited upon input parameter changes as that leads to loss of state
>>> in the filtergraph potentially leading to broken or aborted output,
>>> e.g. inserting of silence with first_pts specified in aresample.
>>>
>>> Generally useful to avoid corrupted yet decodable packets in live
>>> streaming inputs.
>>>
>>> This option when enabled takes precedence over reinit_filters
>>>
>>>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/? 
>>>> a=commit;h=cbbc927a67f142a02bfc5d047c03587599ee5b55
>>> ---
>>
>> This change is causing failed fate tests in many different 
>> configurations; I'm seeing null pointer dereferences and similar, on 
>> both msvc/arm, msvc/x86_32, macos/aarch64. Please investigate.
>
> I pushed a quick fix, but nonetheless, the log message in question is 
> being printed for one stream (the last one handled by the scheduler) 
> rather than every stream where the option was the for, so it needs to 
> be properly done still.

Thanks. FATE passed here and on Patchwork as well.

If ifp can be NULL, how come this pre-existing line above,

           if (ifp->type_src == AVMEDIA_TYPE_SUBTITLE) {

didn't lead to FATE failures?

Re: log, the final log is printed for each stream:

e.g., from the log of a command with option applied to aud and vid,

[af#0:1 @ 000001b4af668380] Total changed input frames dropped : 234
[vf#0:0 @ 000001b4af3e0540] Total changed input frames dropped : 149

Regards,
Gyan