obs-ffmpeg: Do not require encoder ids to be set

For the FFmpeg output, the encoder ids are sort of superfluous.  They
really should be optional.  If they're not set, it should use the
encoder name string instead to determine the ids automatically.

plugins/obs-ffmpeg/obs-ffmpeg-output.c

@@ -448,6 +448,34 @@ static inline const char *safe_str(const char *s)
 		return s;
 }
 
+static enum AVCodecID get_codec_id(const char *name, int id)
+{
+	AVCodec *codec;
+
+	if (id != 0)
+		return (enum AVCodecID)id;
+
+	if (!name || !*name)
+		return AV_CODEC_ID_NONE;
+
+	codec = avcodec_find_encoder_by_name(name);
+	if (!codec)
+		return AV_CODEC_ID_NONE;
+
+	return codec->id;
+}
+
+static void set_encoder_ids(struct ffmpeg_data *data)
+{
+	data->output->oformat->video_codec = get_codec_id(
+			data->config.video_encoder,
+			data->config.video_encoder_id);
+
+	data->output->oformat->audio_codec = get_codec_id(
+			data->config.audio_encoder,
+			data->config.audio_encoder_id);
+}
+
 static bool ffmpeg_data_init(struct ffmpeg_data *data,
 		struct ffmpeg_cfg *config)
 {
@@ -487,12 +515,8 @@ static bool ffmpeg_data_init(struct ffmpeg_data *data,
 		data->output->oformat->video_codec = AV_CODEC_ID_H264;
 		data->output->oformat->audio_codec = AV_CODEC_ID_AAC;
 	} else {
-		if (data->config.format_name) {
-			data->output->oformat->video_codec =
-					data->config.video_encoder_id;
-			data->output->oformat->audio_codec =
-					data->config.audio_encoder_id;
-		}
+		if (data->config.format_name)
+			set_encoder_ids(data);
 	}
 
 	if (!data->output) {