fftools/ffmpeg: refactor the code checking for bitexact output

Figure out earlier whether the output stream/file should be bitexact and
store this information in a flag in OutputFile/OutputStream.

Stop accessing the muxer in set_encoder_id(), which will become
forbidden in future commits.

fftools/ffmpeg.c

@@ -2823,37 +2823,18 @@ static int init_output_stream_streamcopy(OutputStream *ost)
 
 static void set_encoder_id(OutputFile *of, OutputStream *ost)
 {
-    const AVDictionaryEntry *e;
-
     uint8_t *encoder_string;
     int encoder_string_len;
-    int format_flags = 0;
-    int codec_flags = ost->enc_ctx->flags;
 
     if (av_dict_get(ost->st->metadata, "encoder",  NULL, 0))
         return;
 
-    e = av_dict_get(of->opts, "fflags", NULL, 0);
-    if (e) {
-        const AVOption *o = av_opt_find(of->ctx, "fflags", NULL, 0, 0);
-        if (!o)
-            return;
-        av_opt_eval_flags(of->ctx, o, e->value, &format_flags);
-    }
-    e = av_dict_get(ost->encoder_opts, "flags", NULL, 0);
-    if (e) {
-        const AVOption *o = av_opt_find(ost->enc_ctx, "flags", NULL, 0, 0);
-        if (!o)
-            return;
-        av_opt_eval_flags(ost->enc_ctx, o, e->value, &codec_flags);
-    }
-
     encoder_string_len = sizeof(LIBAVCODEC_IDENT) + strlen(ost->enc->name) + 2;
     encoder_string     = av_mallocz(encoder_string_len);
     if (!encoder_string)
         exit_program(1);
 
-    if (!(format_flags & AVFMT_FLAG_BITEXACT) && !(codec_flags & AV_CODEC_FLAG_BITEXACT))
+    if (!of->bitexact && !ost->bitexact)
         av_strlcpy(encoder_string, LIBAVCODEC_IDENT " ", encoder_string_len);
     else
         av_strlcpy(encoder_string, "Lavc ", encoder_string_len);

fftools/ffmpeg.h

@@ -498,6 +498,7 @@ typedef struct OutputStream {
     int top_field_first;
     int rotate_overridden;
     int autoscale;
+    int bitexact;
     int bits_per_raw_sample;
     double rotate_override_value;
 
@@ -598,6 +599,7 @@ typedef struct OutputFile {
     int64_t start_time;      ///< start time in microseconds == AV_TIME_BASE units
 
     int shortest;
+    int bitexact;
 } OutputFile;
 
 extern InputStream **input_streams;

fftools/ffmpeg_opt.c

@@ -1518,6 +1518,22 @@ static int choose_encoder(OptionsContext *o, AVFormatContext *s, OutputStream *o
     return 0;
 }
 
+static int check_opt_bitexact(void *ctx, const AVDictionary *opts,
+                              const char *opt_name, int flag)
+{
+    const AVDictionaryEntry *e = av_dict_get(opts, opt_name, NULL, 0);
+
+    if (e) {
+        const AVOption *o = av_opt_find(ctx, opt_name, NULL, 0, 0);
+        int val = 0;
+        if (!o)
+            return 0;
+        av_opt_eval_flags(ctx, o, e->value, &val);
+        return !!(val & flag);
+    }
+    return 0;
+}
+
 static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, enum AVMediaType type, int source_index)
 {
     OutputStream *ost;
@@ -1610,8 +1626,13 @@ static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, e
     }
 
 
-    if (o->bitexact)
+    if (o->bitexact) {
         ost->enc_ctx->flags |= AV_CODEC_FLAG_BITEXACT;
+        ost->bitexact        = 1;
+    } else {
+        ost->bitexact        = check_opt_bitexact(ost->enc_ctx, ost->encoder_opts, "flags",
+                                                  AV_CODEC_FLAG_BITEXACT);
+    }
 
     MATCH_PER_STREAM_OPT(time_bases, str, time_base, oc, st);
     if (time_base) {
@@ -2424,6 +2445,10 @@ static int open_output_file(OptionsContext *o, const char *filename)
 
     if (o->bitexact) {
         oc->flags    |= AVFMT_FLAG_BITEXACT;
+        of->bitexact  = 1;
+    } else {
+        of->bitexact  = check_opt_bitexact(oc, of->opts, "fflags",
+                                           AVFMT_FLAG_BITEXACT);
     }
 
     /* create streams for all unlabeled output pads */