avformat/hlsenc: enhanced %v handling with variant names

When multiple variant streams are specified by var_stream_map option, %v
placeholder in various names ensures that each variant has its unique
names. Currently %v is substituted by its variant index value (0, 1, 2
etc.). In some use cases it would be handy to specify names for variants
instead of numerical indexes. This patch makes it possible to use names
instead of default indexes. In var_stream_map option each or some of the
variant streams may use an optional name attributum (e.g.
-var_stream_map "v:0,a:0,name:sd v:1,a:1,name:720p") If a name is
specified for a variant, then this name value will be used as
substitution value of %v instead of the default index value.

Signed-off-by: Bela Bodecs <bodecsb@vivanet.hu>
Signed-off-by: Steven Liu <lq@onvideo.cn>

doc/muxers.texi

@@ -943,7 +943,21 @@ This example creates two hls variant streams. The first variant stream will
 contain video stream of bitrate 1000k and audio stream of bitrate 64k and the
 second variant stream will contain video stream of bitrate 256k and audio
 stream of bitrate 32k. Here, two media playlist with file names out_0.m3u8 and
-out_1.m3u8 will be created.
+out_1.m3u8 will be created. If you want something meaningful text instead of indexes
+in result names, you may specify names for each or some of the variants
+as in the following example.
+
+
+@example
+ffmpeg -re -i in.ts -b:v:0 1000k -b:v:1 256k -b:a:0 64k -b:a:1 32k \
+  -map 0:v -map 0:a -map 0:v -map 0:a -f hls -var_stream_map "v:0,a:0,name:my_hd v:1,a:1,name:my_sd" \
+  http://example.com/live/out_%v.m3u8
+@end example
+
+This example creates two hls variant streams as in the previous one.
+But here, the two media playlist with file names out_my_hd.m3u8 and
+out_my_sd.m3u8 will be created.
+
 @example
 ffmpeg -re -i in.ts -b:v:0 1000k -b:v:1 256k -b:a:0 64k \
   -map 0:v -map 0:a -map 0:v -f hls -var_stream_map "v:0 a:0 v:1" \

libavformat/hlsenc.c

@@ -164,6 +164,7 @@ typedef struct VariantStream {
     char *agroup; /* audio group name */
     char *ccgroup; /* closed caption group name */
     char *baseurl;
+    char *varname; // variant name
 } VariantStream;
 
 typedef struct ClosedCaptionsStream {
@@ -340,6 +341,47 @@ fail:
     return;
 }
 
+static int replace_str_data_in_filename(char **s, const char *filename, char placeholder, const char *datastring)
+{
+    const char *p;
+    char *new_filename;
+    char c;
+    int addchar_count;
+    int found_count = 0;
+    AVBPrint buf;
+
+    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
+
+    p = filename;
+    for (;;) {
+        c = *p;
+        if (c == '\0')
+            break;
+        if (c == '%' && *(p+1) == '%')  // %%
+            addchar_count = 2;
+        else if (c == '%' && *(p+1) == placeholder) {
+            av_bprintf(&buf, "%s", datastring);
+            p += 2;
+            addchar_count = 0;
+            found_count ++;
+        } else
+            addchar_count = 1;
+
+        if (addchar_count > 0) {
+            av_bprint_append_data(&buf, p, addchar_count);
+            p += addchar_count;
+        }
+    }
+    if (!av_bprint_is_complete(&buf)) {
+        av_bprint_finalize(&buf, NULL);
+        return -1;
+    }
+    if (av_bprint_finalize(&buf, &new_filename) < 0 || !new_filename)
+        return -1;
+    *s = new_filename;
+    return found_count;
+}
+
 static int replace_int_data_in_filename(char **s, const char *filename, char placeholder, int64_t number)
 {
     const char *p;
@@ -474,20 +516,27 @@ static int hls_delete_old_segments(AVFormatContext *s, HLSContext *hls,
 
     }
 
-    while (segment) {
+    /* if %v is present in the file's directory
+     * all segment belongs to the same variant, so do it only once before the loop*/
+    if (dirname && av_stristr(dirname, "%v")) {
         char * r_dirname = dirname;
-
-        /* if %v is present in the file's directory */
-        if (dirname && av_stristr(dirname, "%v")) {
-
+        if (!vs->varname) {
             if (replace_int_data_in_filename(&r_dirname, dirname, 'v', segment->var_stream_idx) < 1) {
                 ret = AVERROR(EINVAL);
                 goto fail;
             }
-            av_free(dirname);
-            dirname = r_dirname;
+        } else {
+            if (replace_str_data_in_filename(&r_dirname, dirname, 'v', vs->varname) < 1) {
+                ret = AVERROR(EINVAL);
+                goto fail;
+            }
         }
 
+        av_free(dirname);
+        dirname = r_dirname;
+    }
+
+    while (segment) {
         av_log(hls, AV_LOG_DEBUG, "deleting old segment %s\n",
                                   segment->filename);
         path_size =  (hls->use_localtime_mkdir ? 0 : strlen(dirname)) + strlen(segment->filename) + 1;
@@ -1761,7 +1810,7 @@ fail:
     return ret;
 }
 
-static int format_name(const char *buf, char **s, int index)
+static int format_name(const char *buf, char **s, int index, const char *varname)
 {
     const char *proto, *dir;
     char *orig_buf_dup = NULL, *mod_buf_dup = NULL;
@@ -1778,9 +1827,16 @@ static int format_name(const char *buf, char **s, int index)
         return ret;
     }
 
-    if (replace_int_data_in_filename(s, orig_buf_dup, 'v', index) < 1) {
-        ret = AVERROR(EINVAL);
-        goto fail;
+    if (!varname) {
+        if (replace_int_data_in_filename(s, orig_buf_dup, 'v', index) < 1) {
+            ret = AVERROR(EINVAL);
+            goto fail;
+        }
+    } else {
+        if (replace_str_data_in_filename(s, orig_buf_dup, 'v', varname) < 1) {
+            ret = AVERROR(EINVAL);
+            goto fail;
+        }
     }
 
     proto = avio_find_protocol_name(orig_buf_dup);
@@ -1898,6 +1954,11 @@ static int parse_variant_stream_mapstring(AVFormatContext *s)
                                   (!av_strncasecmp(val, "1", strlen("1"))));
                 hls->has_default_key = 1;
                 continue;
+            } else if (av_strstart(keyval, "name:", &val)) {
+                vs->varname = av_strdup(val);
+                if (!vs->varname)
+                    return AVERROR(ENOMEM);
+                continue;
             } else if (av_strstart(keyval, "agroup:", &val)) {
                 vs->agroup = av_strdup(val);
                 if (!vs->agroup)
@@ -2417,6 +2478,7 @@ static void hls_free_variant_streams(struct HLSContext *hls)
         av_freep(&vs->language);
         av_freep(&vs->ccgroup);
         av_freep(&vs->baseurl);
+        av_freep(&vs->varname);
     }
 }
 
@@ -2629,12 +2691,7 @@ static int hls_init(AVFormatContext *s)
     for (i = 0; i < hls->nb_varstreams; i++) {
         vs = &hls->var_streams[i];
 
-        vs->m3u8_name = av_strdup(s->url);
-        if (!vs->m3u8_name ) {
-            ret = AVERROR(ENOMEM);
-            goto fail;
-        }
-        ret = format_name(s->url, i, vs->m3u8_name);
+        ret = format_name(s->url, &vs->m3u8_name, i, vs->varname);
         if (ret < 0)
             goto fail;
 
@@ -2695,17 +2752,10 @@ static int hls_init(AVFormatContext *s)
             }
         }
         if (hls->segment_filename) {
-            basename_size = strlen(hls->segment_filename) + 1;
-            vs->basename = av_malloc(basename_size);
-            if (!vs->basename) {
-                ret = AVERROR(ENOMEM);
-                goto fail;
-            }
-
-            av_strlcpy(vs->basename, hls->segment_filename, basename_size);
-            ret = format_name(vs->basename, basename_size, i);
+            ret = format_name(hls->segment_filename, &vs->basename, i, vs->varname);
             if (ret < 0)
                 goto fail;
+            basename_size = strlen(vs->basename) + 1;
         } else {
             if (hls->flags & HLS_SINGLE_FILE) {
                 if (hls->segment_type == SEGMENT_TYPE_FMP4) {
@@ -2758,7 +2808,8 @@ static int hls_init(AVFormatContext *s)
                            fmp4_init_filename_len);
                 if (hls->nb_varstreams > 1) {
                     if (av_stristr(vs->fmp4_init_filename, "%v")) {
-                        format_name(vs->fmp4_init_filename, fmp4_init_filename_len, i);
+                        av_freep(&vs->fmp4_init_filename);
+                        format_name(hls->fmp4_init_filename, &vs->fmp4_init_filename, i, vs->varname);
                     } else {
                         ret = append_postfix(vs->fmp4_init_filename, fmp4_init_filename_len, i);
                     }
@@ -2822,8 +2873,8 @@ static int hls_init(AVFormatContext *s)
                 *p = '\0';
 
             if ( hls->subtitle_filename ) {
-                strcpy(vs->vtt_m3u8_name, hls->subtitle_filename);
-                ret = format_name(vs->vtt_m3u8_name, vtt_basename_size, i);
+                av_freep(&vs->vtt_m3u8_name);
+                ret = format_name(hls->subtitle_filename, &vs->vtt_m3u8_name, i, vs->varname);
                 if (ret < 0)
                     goto fail;
             } else {
@@ -2874,6 +2925,7 @@ fail:
             av_freep(&vs->agroup);
             av_freep(&vs->ccgroup);
             av_freep(&vs->baseurl);
+            av_freep(&vs->varname);
             if (vs->avf)
                 avformat_free_context(vs->avf);
             if (vs->vtt_avf)