Fixing the erratic live MP4 feed, caching the active font (a must for

dynamic OSDs with stable attributes)

Author: wberube

src/fmt/mp4.c

@@ -1,8 +1,9 @@
 #include "mp4.h"
 
 uint32_t default_sample_size = 40000;
+uint32_t last_fragment_duration, timescale;
 
-unsigned int aud_samplerate = 0, aud_framesize = 0;
+unsigned int aud_samplerate = 0;
 unsigned short aud_bitrate = 0;
 char aud_channels = 0, aud_codec = 0, vid_framerate = 30;
 short vid_width = 1920, vid_height = 1080;
@@ -42,8 +43,8 @@ enum BufError create_header(char is_h265) {
     moov_info.horizontal_resolution = 0x00480000; // 72 dpi
     moov_info.vertical_resolution = 0x00480000;   // 72 dpi
     moov_info.creation_time = 0;
-    moov_info.timescale =
-        default_sample_size * vid_framerate;
+    timescale = default_sample_size * vid_framerate;
+    moov_info.timescale = timescale;
     moov_info.sps = buf_sps;
     moov_info.sps_length = buf_sps_len;
     moov_info.pps = buf_pps;
@@ -66,13 +67,6 @@ void mp4_set_config(short width, short height, char framerate, char acodec,
     aud_bitrate = bitrate;
     aud_channels = channels;
     aud_samplerate = srate;
-    if (aud_samplerate > 0) {
-        aud_framesize = 
-            (aud_samplerate >= 32000 ? 144 : 72) *
-            (aud_bitrate * 1000) / 
-            aud_samplerate;
-    } else aud_framesize = 384;
-
 }
 
 void mp4_set_sps(const char *nal_data, const uint32_t nal_len, char is_h265) {
@@ -95,6 +89,7 @@ void mp4_set_vps(const char *nal_data, const uint32_t nal_len) {
 
 enum BufError mp4_set_slice(const char *nal_data, const uint32_t nal_len,
     char is_iframe) {
+    uint64_t aud_ticks;
     enum BufError err;
 
     struct SampleInfo samples_info[2];
@@ -103,8 +98,12 @@ enum BufError mp4_set_slice(const char *nal_data, const uint32_t nal_len,
     samples_info[0].duration = default_sample_size;
     samples_info[0].flags = is_iframe ? 0 : 65536;
     samples_info[1].size = buf_aud.offset;
-    samples_info[1].duration = default_sample_size * 
-        buf_aud.offset / (aud_bitrate * 25 / 6);
+    if (aud_bitrate > 0)
+        aud_ticks = ((uint64_t)(buf_aud.offset << 3) * timescale) /
+            (aud_bitrate * 1000);
+    samples_info[1].duration = (uint32_t)aud_ticks;
+    last_fragment_duration =
+        MAX(samples_info[1].duration, samples_info[0].duration);
 
     buf_moof.offset = 0;
     err = write_moof(
@@ -113,7 +112,7 @@ enum BufError mp4_set_slice(const char *nal_data, const uint32_t nal_len,
     chk_err;
 
     buf_mdat.offset = 0;
-    err = write_mdat(&buf_mdat, nal_data, nal_len, 
+    err = write_mdat(&buf_mdat, nal_data, nal_len,
         buf_aud.buf, buf_aud.offset);
     chk_err;
 
@@ -145,7 +144,7 @@ enum BufError mp4_set_state(struct Mp4State *state) {
         state->base_media_decode_time);
     chk_err state->sequence_number++;
     state->base_data_offset += buf_moof.offset + buf_mdat.offset;
-    state->base_media_decode_time += state->default_sample_duration;
+    state->base_media_decode_time += last_fragment_duration;
     return BUF_OK;
 }
 
@@ -168,4 +167,4 @@ enum BufError mp4_get_moof(struct BitBuf *ptr) {
     ptr->size = buf_moof.size;
     ptr->offset = buf_moof.offset;
     return BUF_OK;
-}
+}

src/fmt/mp4.h

@@ -39,4 +39,4 @@ enum BufError mp4_set_state(struct Mp4State *state);
 
 enum BufError mp4_get_header(struct BitBuf *ptr);
 enum BufError mp4_get_moof(struct BitBuf *ptr);
-enum BufError mp4_get_mdat(struct BitBuf *ptr);
+enum BufError mp4_get_mdat(struct BitBuf *ptr);

src/text.c

@@ -2,12 +2,16 @@
 
 const double inv255 = 1.0 / 255.0;
 
+static SFT_Font *cachedFont = NULL;
+static char cachedFontPath[256] = "";
+static double cachedFontSize = -1.0;
+
 SFT sft;
 SFT_Image canvas;
 SFT_LMetrics lmtx;
 hal_bitmap bitmap;
 
-int utf8_to_utf32(const unsigned char *utf8, 
+int utf8_to_utf32(const unsigned char *utf8,
     unsigned int *utf32, int max)
 {
     unsigned int c;
@@ -87,26 +91,35 @@ void text_copy_rendered(SFT_Image *dest, const SFT_Image *source, int x0, int y0
 
 int text_load_font(SFT *sft, const char *path, double size, SFT_LMetrics *lmtx)
 {
-    SFT_Font *font = sft_loadfile(path);
-    if (font == NULL)
-        HAL_ERROR("text", "sft_loadfile failed");
-    sft->font = font;
+    if (!cachedFont || cachedFontSize != size || !EQUALS(cachedFontPath, path)) {
+        if (cachedFont)
+            sft_freefont(cachedFont);
+        cachedFont = sft_loadfile(path);
+        if (!cachedFont)
+            HAL_ERROR("text", "Unable to load font file '%s'!", path);
+        strncpy(cachedFontPath, path, sizeof(cachedFontPath));
+        cachedFontPath[sizeof(cachedFontPath) - 1] = '\0';
+        cachedFontSize = size;
+    }
+
+    sft->font = cachedFont;
     sft->xScale = size;
     sft->yScale = size;
     sft->xOffset = 0.0;
     sft->yOffset = 0.0;
     sft->flags = SFT_DOWNWARD_Y;
     if (sft_lmetrics(sft, lmtx) < 0)
-        HAL_ERROR("text", "sft_lmetrics failed");
+        HAL_ERROR("text", "Unable to read font metrics for '%s' (size %.2f)!", path, size);
+
     return EXIT_SUCCESS;
 }
 
 int text_load_glyph(const SFT *sft, SFT_UChar codepoint, SFT_Glyph *glyph, SFT_GMetrics *metrics)
 {
     if (sft_lookup(sft, codepoint, glyph) < 0)
-        HAL_ERROR("text", "sft_lookup failed");
+        HAL_ERROR("text", "Cannot find glyph for codepoint U+%04X!", codepoint);
     if (sft_gmetrics(sft, *glyph, metrics) < 0)
-        HAL_ERROR("text", "sft_gmetrics failed");
+        HAL_ERROR("text", "Cannot read metrics for glyph U+%04X!", codepoint);
     return EXIT_SUCCESS;
 }
 
@@ -153,7 +166,7 @@ void text_dim_rendered(double *margin, double *height, double *width, const char
     *width = MAX(*width, lwidth) + 2 * *margin;
 }
 
-hal_bitmap text_create_rendered(const char *font, double size, const char *text, 
+hal_bitmap text_create_rendered(const char *font, double size, const char *text,
     int color, int outline, double thick)
 {
     text_load_font(&sft, font, size, &lmtx);
@@ -212,6 +225,5 @@ noOutline:;
     bitmap.dim.height = canvas.height;
     bitmap.data = canvas.pixels;
 
-    sft_freefont(sft.font);
     return bitmap;
-}
+}