Warn user if bitrate parameter is too low

Originally committed as revision 10919 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffmpeg.c

@@ -2159,6 +2159,16 @@ static void opt_frame_rate(const char *arg)
     }
 }
 
+static void opt_bitrate(const char *opt, const char *arg)
+{
+    int codec_type = opt[0]=='a' ? CODEC_TYPE_AUDIO : CODEC_TYPE_VIDEO;
+
+    opt_default(opt, arg);
+
+    if (av_get_int(avctx_opts[codec_type], "b", NULL) < 1000)
+        fprintf(stderr, "WARNING: The bitrate parameter is set too low. It takes bits/s as argument, not kbits/s\n");
+}
+
 static void opt_frame_crop_top(const char *arg)
 {
     frame_topBand = atoi(arg);
@@ -3688,6 +3698,8 @@ const OptionDef options[] = {
     { "programid", HAS_ARG | OPT_INT | OPT_EXPERT, {(void*)&opt_programid}, "desired program number", "" },
 
     /* video options */
+    { "b", OPT_FUNC2 | HAS_ARG | OPT_VIDEO, {(void*)opt_bitrate}, "set bitrate (in bits/s)", "" },
+    { "vb", OPT_FUNC2 | HAS_ARG | OPT_VIDEO, {(void*)opt_bitrate}, "set bitrate (in bits/s)", "" },
     { "vframes", OPT_INT | HAS_ARG | OPT_VIDEO, {(void*)&max_frames[CODEC_TYPE_VIDEO]}, "set the number of video frames to record", "number" },
     { "dframes", OPT_INT | HAS_ARG, {(void*)&max_frames[CODEC_TYPE_DATA]}, "set the number of data frames to record", "number" },
     { "r", HAS_ARG | OPT_VIDEO, {(void*)opt_frame_rate}, "set frame rate (Hz value, fraction or abbreviation)", "rate" },
@@ -3734,6 +3746,7 @@ const OptionDef options[] = {
     { "qphist", OPT_BOOL | OPT_EXPERT | OPT_VIDEO, { (void *)&qp_hist }, "show QP histogram" },
 
     /* audio options */
+    { "ab", OPT_FUNC2 | HAS_ARG | OPT_AUDIO, {(void*)opt_bitrate}, "set bitrate (in bits/s)", "" },
     { "aframes", OPT_INT | HAS_ARG | OPT_AUDIO, {(void*)&max_frames[CODEC_TYPE_AUDIO]}, "set the number of audio frames to record", "number" },
     { "aq", OPT_FLOAT | HAS_ARG | OPT_AUDIO, {(void*)&audio_qscale}, "set audio quality (codec-specific)", "quality", },
     { "ar", HAS_ARG | OPT_AUDIO, {(void*)opt_audio_rate}, "set audio sampling rate (in Hz)", "rate" },