fftools/ffmpeg_demux: add InputStreamGroup to store stream groups

Preparatory work for upcoming changes. Make ffmpeg keep track of stream groups
internally.

Signed-off-by: James Almer <jamrial@gmail.com>

fftools/ffmpeg.h

@@ -492,6 +492,17 @@ typedef struct InputStream {
     int                nb_filters;
 } InputStream;
 
+typedef struct InputStreamGroup {
+    const AVClass        *class;
+
+    /* parent source */
+    struct InputFile     *file;
+
+    int                   index;
+
+    AVStreamGroup        *stg;
+} InputStreamGroup;
+
 typedef struct InputFile {
     const AVClass   *class;
 
@@ -513,6 +524,10 @@ typedef struct InputFile {
      * if new streams appear dynamically during demuxing */
     InputStream    **streams;
     int           nb_streams;
+
+    /* stream groups that ffmpeg is aware of; */
+    InputStreamGroup **stream_groups;
+    int           nb_stream_groups;
 } InputFile;
 
 enum forced_keyframes_const {

fftools/ffmpeg_demux.c

@@ -104,6 +104,13 @@ typedef struct DemuxStream {
     int64_t                  lag;
 } DemuxStream;
 
+typedef struct DemuxStreamGroup {
+    InputStreamGroup         istg;
+
+    // name used for logging
+    char                     log_name[32];
+} DemuxStreamGroup;
+
 typedef struct Demuxer {
     InputFile             f;
 
@@ -886,6 +893,16 @@ static void ist_free(InputStream **pist)
     av_freep(pist);
 }
 
+static void istg_free(InputStreamGroup **pistg)
+{
+    InputStreamGroup *istg = *pistg;
+
+    if (!istg)
+        return;
+
+    av_freep(pistg);
+}
+
 void ifile_close(InputFile **pf)
 {
     InputFile *f = *pf;
@@ -901,6 +918,10 @@ void ifile_close(InputFile **pf)
         ist_free(&f->streams[i]);
     av_freep(&f->streams);
 
+    for (int i = 0; i < f->nb_stream_groups; i++)
+        istg_free(&f->stream_groups[i]);
+    av_freep(&f->stream_groups);
+
     avformat_close_input(&f->ctx);
 
     av_packet_free(&d->pkt_heartbeat);
@@ -1586,6 +1607,51 @@ static int ist_add(const OptionsContext *o, Demuxer *d, AVStream *st, AVDictiona
     return 0;
 }
 
+static const char *input_stream_group_item_name(void *obj)
+{
+    const DemuxStreamGroup *dsg = obj;
+
+    return dsg->log_name;
+}
+
+static const AVClass input_stream_group_class = {
+    .class_name = "InputStreamGroup",
+    .version    = LIBAVUTIL_VERSION_INT,
+    .item_name  = input_stream_group_item_name,
+    .category   = AV_CLASS_CATEGORY_DEMUXER,
+};
+
+static DemuxStreamGroup *demux_stream_group_alloc(Demuxer *d, AVStreamGroup *stg)
+{
+    InputFile    *f = &d->f;
+    DemuxStreamGroup *dsg;
+
+    dsg = allocate_array_elem(&f->stream_groups, sizeof(*dsg), &f->nb_stream_groups);
+    if (!dsg)
+        return NULL;
+
+    dsg->istg.stg        = stg;
+    dsg->istg.file       = f;
+    dsg->istg.index      = stg->index;
+    dsg->istg.class      = &input_stream_group_class;
+
+    snprintf(dsg->log_name, sizeof(dsg->log_name), "istg#%d:%d/%s",
+             d->f.index, stg->index, avformat_stream_group_name(stg->type));
+
+    return dsg;
+}
+
+static int istg_add(const OptionsContext *o, Demuxer *d, AVStreamGroup *stg)
+{
+    DemuxStreamGroup *dsg;
+
+    dsg = demux_stream_group_alloc(d, stg);
+    if (!dsg)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
 static int dump_attachment(InputStream *ist, const char *filename)
 {
     AVStream *st = ist->st;
@@ -1954,6 +2020,13 @@ int ifile_open(const OptionsContext *o, const char *filename, Scheduler *sch)
         }
     }
 
+    /* Add all the stream groups from the given input file to the demuxer */
+    for (int i = 0; i < ic->nb_stream_groups; i++) {
+        ret = istg_add(o, d, ic->stream_groups[i]);
+        if (ret < 0)
+            return ret;
+    }
+
     /* dump the file content */
     av_dump_format(ic, f->index, filename, 0);