[FFmpeg-devel] [PATCH v1 1/2] avformat/imfdec: use CPL start timecode if available

[pal@sandflow.com]

From: Pierre-Anthony Lemieux <pal@palemieux.com>

The IMF CPL contains an optional timecode start address. This patch reads the
latter, if present, into the context's timecode metadata parameter.
This addresses https://trac.ffmpeg.org/ticket/9842.

---
 libavformat/imf.h     |   2 +
 libavformat/imf_cpl.c | 109 ++++++++++++++++++++++++++++++++++++++++++
 libavformat/imfdec.c  |  11 +++++
 3 files changed, 122 insertions(+)

diff --git a/libavformat/imf.h b/libavformat/imf.h
index 4271cd9582..70ed007312 100644
--- a/libavformat/imf.h
+++ b/libavformat/imf.h
@@ -59,6 +59,7 @@
 #include "libavformat/avio.h"
 #include "libavutil/rational.h"
 #include "libavutil/uuid.h"
+#include "libavutil/timecode.h"
 #include <libxml/tree.h>
 
 /**
@@ -130,6 +131,7 @@ typedef struct FFIMFCPL {
     AVUUID id_uuid;                               /**< CompositionPlaylist/Id element */
     xmlChar *content_title_utf8;                     /**< CompositionPlaylist/ContentTitle element */
     AVRational edit_rate;                            /**< CompositionPlaylist/EditRate element */
+    AVTimecode *tc;                                  /**< CompositionPlaylist/CompositionTimecode element */
     FFIMFMarkerVirtualTrack *main_markers_track;     /**< Main Marker Virtual Track */
     FFIMFTrackFileVirtualTrack *main_image_2d_track; /**< Main Image Virtual Track */
     uint32_t main_audio_track_count;                 /**< Number of Main Audio Virtual Tracks */
diff --git a/libavformat/imf_cpl.c b/libavformat/imf_cpl.c
index 4acc20feee..1868d7db45 100644
--- a/libavformat/imf_cpl.c
+++ b/libavformat/imf_cpl.c
@@ -116,6 +116,25 @@ int ff_imf_xml_read_uint32(xmlNodePtr element, uint32_t *number)
     return ret;
 }
 
+static int ff_imf_xml_read_boolean(xmlNodePtr element, int *value)
+{
+    xmlChar *element_text = NULL;
+    int ret = 0;
+
+    element_text = xmlNodeListGetString(element->doc, element->xmlChildrenNode, 1);
+
+    if (xmlStrcmp(element_text, "true") == 0 || xmlStrcmp(element_text, "1") == 0)
+        *value = 1;
+    else if (xmlStrcmp(element_text, "false") == 0 || xmlStrcmp(element_text, "0") == 0)
+        *value = 0;
+    else
+        ret = 1;
+
+    xmlFree(element_text);
+
+    return ret;
+}
+
 static void imf_base_virtual_track_init(FFIMFBaseVirtualTrack *track)
 {
     memset(track->id_uuid, 0, sizeof(track->id_uuid));
@@ -179,6 +198,90 @@ static int fill_content_title(xmlNodePtr cpl_element, FFIMFCPL *cpl)
     return 0;
 }
 
+static int digit_to_int(char digit)
+{
+    if (digit >= '0' && digit <= '9')
+        return digit - '0';
+    return -1;
+}
+
+/**
+ * Parses a string that conform to the TimecodeType used in IMF CPL and defined
+ * in SMPTE ST 2067-3.
+ * @param[in] s string to parse
+ * @param[out] tc_comps pointer to an array of 4 integers where the parsed HH,
+ *                      MM, SS and FF fields of the timecode are returned.
+ * @return 0 on success, < 0 AVERROR code on error.
+ */
+static int parse_cpl_tc_type(const char *s, int *tc_comps)
+{
+    if (av_strnlen(s, 11) != 11)
+        return AVERROR(EINVAL);
+
+    for (int i = 0; i < 4; i++) {
+        int hi;
+        int lo;
+
+        hi = digit_to_int(s[i * 3]);
+        lo = digit_to_int(s[i * 3 + 1]);
+
+        if (hi == -1 || lo == -1)
+            return AVERROR(EINVAL);
+
+        tc_comps[i] = 10 * hi + lo;
+    }
+
+    return 0;
+}
+
+static int fill_timecode(xmlNodePtr cpl_element, FFIMFCPL *cpl)
+{
+    xmlNodePtr tc_element = NULL;
+    xmlNodePtr element = NULL;
+    xmlChar *tc_str = NULL;
+    int df = 0;
+    int comps[4];
+    int ret = 0;
+
+    tc_element = ff_imf_xml_get_child_element_by_name(cpl_element, "CompositionTimecode");
+    if (!tc_element)
+       return 0;
+
+    element = ff_imf_xml_get_child_element_by_name(tc_element, "TimecodeDropFrame");
+    if (!element) {
+        av_log(NULL, AV_LOG_ERROR, "CompositionTimecode element is missing\
+                                    a TimecodeDropFrame child element\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    if (ff_imf_xml_read_boolean(element, &df)) {
+        av_log(NULL, AV_LOG_ERROR, "TimecodeDropFrame element is invalid\n");
+        return AVERROR_INVALIDDATA;
+    }
+    element = ff_imf_xml_get_child_element_by_name(tc_element, "TimecodeStartAddress");
+    if (!element) {
+        av_log(NULL, AV_LOG_ERROR, "CompositionTimecode element is missing\
+                                    a TimecodeStartAddress child element\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    tc_str = xmlNodeListGetString(element->doc, element->xmlChildrenNode, 1);
+    ret = parse_cpl_tc_type(tc_str, comps);
+    xmlFree(tc_str);
+    if (ret)
+        return ret;
+
+    cpl->tc = av_malloc(sizeof(AVTimecode));
+    if (!cpl->tc)
+        return AVERROR(ENOMEM);
+    ret = av_timecode_init_from_components(cpl->tc, cpl->edit_rate,
+                                           df ? AV_TIMECODE_FLAG_DROPFRAME : 0,
+                                           comps[0], comps[1], comps[2], comps[3],
+                                           NULL);
+
+    return ret;
+}
+
 static int fill_edit_rate(xmlNodePtr cpl_element, FFIMFCPL *cpl)
 {
     xmlNodePtr element = NULL;
@@ -682,6 +785,8 @@ int ff_imf_parse_cpl_from_xml_dom(xmlDocPtr doc, FFIMFCPL **cpl)
         goto cleanup;
     if ((ret = fill_edit_rate(cpl_element, *cpl)))
         goto cleanup;
+    if ((ret = fill_timecode(cpl_element, *cpl)))
+        goto cleanup;
     if ((ret = fill_virtual_tracks(cpl_element, *cpl)))
         goto cleanup;
 
@@ -731,6 +836,7 @@ static void imf_cpl_init(FFIMFCPL *cpl)
     av_uuid_nil(cpl->id_uuid);
     cpl->content_title_utf8 = NULL;
     cpl->edit_rate = av_make_q(0, 1);
+    cpl->tc = NULL;
     cpl->main_markers_track = NULL;
     cpl->main_image_2d_track = NULL;
     cpl->main_audio_track_count = 0;
@@ -753,6 +859,9 @@ void ff_imf_cpl_free(FFIMFCPL *cpl)
     if (!cpl)
         return;
 
+    if (cpl->tc)
+        av_freep(&cpl->tc);
+
     xmlFree(cpl->content_title_utf8);
 
     imf_marker_virtual_track_free(cpl->main_markers_track);
diff --git a/libavformat/imfdec.c b/libavformat/imfdec.c
index 5bbe7a53f8..fdf9a4e87c 100644
--- a/libavformat/imfdec.c
+++ b/libavformat/imfdec.c
@@ -622,6 +622,8 @@ static int imf_read_header(AVFormatContext *s)
     IMFContext *c = s->priv_data;
     char *asset_map_path;
     char *tmp_str;
+    AVDictionaryEntry* tcr;
+    char tc_buf[AV_TIMECODE_STR_SIZE];
     int ret = 0;
 
     c->interrupt_callback = &s->interrupt_callback;
@@ -641,6 +643,15 @@ static int imf_read_header(AVFormatContext *s)
     if ((ret = ff_imf_parse_cpl(s->pb, &c->cpl)) < 0)
         return ret;
 
+    tcr = av_dict_get(s->metadata, "timecode", NULL, 0);
+    if (!tcr && c->cpl->tc) {
+        ret = av_dict_set(&s->metadata, "timecode",
+                          av_timecode_make_string(c->cpl->tc, tc_buf, 0), 0);
+        if (ret)
+            return ret;
+        av_log(s, AV_LOG_INFO, "Setting timecode to IMF CPL timecode %s\n", tc_buf);
+    }
+
     av_log(s,
            AV_LOG_DEBUG,
            "parsed IMF CPL: " AV_PRI_URN_UUID "\n",
-- 
2.25.1

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