ffmpeg learning diary 513-source code-configure_filtergraph() function analysis and function

Date: 12/04/2023
Hours:
Details:

template_tags

source version

ffmpeg-4.1.10

implementation file

fftools/ffmpeg_filter.c

function prototype

int configure_filtergraph(FilterGraph *fg)

Parameter interpretation

• fg: the structure pointer of the incoming filter graph
• Return value: return 0 if correct, return <0 if failed

function function

function analysis

filtergraph_is_simple function

filtergraph_is_simple is implemented as follows:

int filtergraph_is_simple(FilterGraph *fg)
{
    return !fg->graph_desc;
}

The string field of the filter is stored in graph_desc, graph_desc is a string value, plus! In the future, it should return 0 or 1, although the return value type is int, call it below

const char *graph_desc = simple ? fg->outputs[0]->ost->avfilter :
                                      fg->graph_desc;

The logic of this processing as a bool value is further verified.

Using breakpoint debugging, the debugging result is consistent with the above conjecture

next is

cleanup_filtergraph(fg);

Summarize

reference