ffmpeg: take bsf arguments from the command line

The format is now:
-bsf:X filter1[=opt1=str1/opt2=str2],filter2
ie the parameters are appended after the filter name using '='. As ','
has been reserved already for the list of filters, '/' is just an
example of token separation for now, but that could become part of the
API to avoid each bsf using its own tokenization.

The proper solution would be using AVOption, but this is overkill for now.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

doc/bitstream_filters.texi

@@ -13,6 +13,14 @@ bitstream filter using the option @code{--disable-bsf=BSF}.
 The option @code{-bsfs} of the ff* tools will display the list of
 all the supported bitstream filters included in your build.
 
+The ff* tools have a -bsf option applied per stream, taking a
+comma-separated list of filters, whose parameters follow the filter
+name after a '='.
+
+@example
+ffmpeg -i INPUT -c:v copy -bsf:v filter1[=opt1=str1/opt2=str2][,filter2] OUTPUT
+@end example
+
 Below is a description of the currently available bitstream filters.
 
 @section aac_adtstoasc

ffmpeg.c

@@ -623,7 +623,11 @@ static void write_frame(AVFormatContext *s, AVPacket *pkt, OutputStream *ost)
 
     while (bsfc) {
         AVPacket new_pkt = *pkt;
-        int a = av_bitstream_filter_filter(bsfc, avctx, NULL,
+        AVDictionaryEntry *bsf_arg = av_dict_get(ost->bsf_args,
+                                                 bsfc->filter->name,
+                                                 NULL, 0);
+        int a = av_bitstream_filter_filter(bsfc, avctx,
+                                           bsf_arg ? bsf_arg->value : NULL,
                                            &new_pkt.data, &new_pkt.size,
                                            pkt->data, pkt->size,
                                            pkt->flags & AV_PKT_FLAG_KEY);
@@ -3834,6 +3838,7 @@ static int transcode(void)
                 av_dict_free(&ost->encoder_opts);
                 av_dict_free(&ost->swr_opts);
                 av_dict_free(&ost->resample_opts);
+                av_dict_free(&ost->bsf_args);
             }
         }
     }

ffmpeg.h

@@ -422,6 +422,7 @@ typedef struct OutputStream {
     AVDictionary *encoder_opts;
     AVDictionary *swr_opts;
     AVDictionary *resample_opts;
+    AVDictionary *bsf_args;
     char *apad;
     OSTFinished finished;        /* no more packets should be written for this stream */
     int unavailable;                     /* true if the steram is unavailable (possibly temporarily) */

ffmpeg_opt.c

@@ -1138,8 +1138,11 @@ static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, e
 
     MATCH_PER_STREAM_OPT(bitstream_filters, str, bsf, oc, st);
     while (bsf) {
+        char *arg = NULL;
         if (next = strchr(bsf, ','))
             *next++ = 0;
+        if (arg = strchr(bsf, '='))
+            *arg++ = 0;
         if (!(bsfc = av_bitstream_filter_init(bsf))) {
             av_log(NULL, AV_LOG_FATAL, "Unknown bitstream filter %s\n", bsf);
             exit_program(1);
@@ -1148,6 +1151,7 @@ static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, e
             bsfc_prev->next = bsfc;
         else
             ost->bitstream_filters = bsfc;
+        av_dict_set(&ost->bsf_args, bsfc->filter->name, arg, 0);
 
         bsfc_prev = bsfc;
         bsf       = next;