output-example: K&R formatting cosmetics, comment spelling fixes

libavformat/output-example.c

@@ -86,7 +86,7 @@ static AVStream *add_audio_stream(AVFormatContext *oc, enum CodecID codec_id)
     c->channels    = 2;
 
     // some formats want stream headers to be separate
-    if(oc->oformat->flags & AVFMT_GLOBALHEADER)
+    if (oc->oformat->flags & AVFMT_GLOBALHEADER)
         c->flags |= CODEC_FLAG_GLOBAL_HEADER;
 
     return st;
@@ -114,21 +114,22 @@ static void open_audio(AVFormatContext *oc, AVStream *st)
         audio_input_frame_size = 10000;
     else
         audio_input_frame_size = c->frame_size;
-    samples = av_malloc(audio_input_frame_size * av_get_bytes_per_sample(c->sample_fmt)
-                        * c->channels);
+    samples = av_malloc(audio_input_frame_size *
+                        av_get_bytes_per_sample(c->sample_fmt) *
+                        c->channels);
 }
 
-/* prepare a 16 bit dummy audio frame of 'frame_size' samples and
-   'nb_channels' channels */
+/* Prepare a 16 bit dummy audio frame of 'frame_size' samples and
+ * 'nb_channels' channels. */
 static void get_audio_frame(int16_t *samples, int frame_size, int nb_channels)
 {
     int j, i, v;
     int16_t *q;
 
     q = samples;
-    for(j=0;j<frame_size;j++) {
+    for (j = 0; j < frame_size; j++) {
         v = (int)(sin(t) * 10000);
-        for(i = 0; i < nb_channels; i++)
+        for (i = 0; i < nb_channels; i++)
             *q++ = v;
         t     += tincr;
         tincr += tincr2;
@@ -147,17 +148,19 @@ static void write_audio_frame(AVFormatContext *oc, AVStream *st)
 
     get_audio_frame(samples, audio_input_frame_size, c->channels);
     frame->nb_samples = audio_input_frame_size;
-    avcodec_fill_audio_frame(frame, c->channels, c->sample_fmt, (uint8_t *)samples,
-                             audio_input_frame_size * av_get_bytes_per_sample(c->sample_fmt)
-                             * c->channels, 1);
+    avcodec_fill_audio_frame(frame, c->channels, c->sample_fmt,
+                             (uint8_t *)samples,
+                             audio_input_frame_size *
+                             av_get_bytes_per_sample(c->sample_fmt) *
+                             c->channels, 1);
 
     avcodec_encode_audio2(c, &pkt, frame, &got_packet);
     if (!got_packet)
         return;
 
-    pkt.stream_index= st->index;
+    pkt.stream_index = st->index;
 
-    /* write the compressed frame in the media file */
+    /* Write the compressed frame to the media file. */
     if (av_interleaved_write_frame(oc, &pkt) != 0) {
         fprintf(stderr, "Error while writing audio frame\n");
         exit(1);
@@ -178,7 +181,7 @@ static AVFrame *picture, *tmp_picture;
 static uint8_t *video_outbuf;
 static int frame_count, video_outbuf_size;
 
-/* add a video output stream */
+/* Add a video output stream. */
 static AVStream *add_video_stream(AVFormatContext *oc, enum CodecID codec_id)
 {
     AVCodecContext *c;
@@ -200,15 +203,15 @@ static AVStream *add_video_stream(AVFormatContext *oc, enum CodecID codec_id)
 
     c = st->codec;
 
-    /* put sample parameters */
+    /* Put sample parameters. */
     c->bit_rate = 400000;
-    /* resolution must be a multiple of two */
+    /* Resolution must be a multiple of two. */
     c->width    = 352;
     c->height   = 288;
-    /* time base: this is the fundamental unit of time (in seconds) in terms
-       of which frame timestamps are represented. for fixed-fps content,
-       timebase should be 1/framerate and timestamp increments should be
-       identically 1. */
+    /* timebase: This is the fundamental unit of time (in seconds) in terms
+     * of which frame timestamps are represented. For fixed-fps content,
+     * timebase should be 1/framerate and timestamp increments should be
+     * identical to 1. */
     c->time_base.den = STREAM_FRAME_RATE;
     c->time_base.num = 1;
     c->gop_size      = 12; /* emit one intra frame every twelve frames at most */
@@ -217,14 +220,14 @@ static AVStream *add_video_stream(AVFormatContext *oc, enum CodecID codec_id)
         /* just for testing, we also add B frames */
         c->max_b_frames = 2;
     }
-    if (c->codec_id == CODEC_ID_MPEG1VIDEO){
+    if (c->codec_id == CODEC_ID_MPEG1VIDEO) {
         /* Needed to avoid using macroblocks in which some coeffs overflow.
-           This does not happen with normal video, it just happens here as
-           the motion of the chroma plane does not match the luma plane. */
-        c->mb_decision=2;
+         * This does not happen with normal video, it just happens here as
+         * the motion of the chroma plane does not match the luma plane. */
+        c->mb_decision = 2;
     }
-    // some formats want stream headers to be separate
-    if(oc->oformat->flags & AVFMT_GLOBALHEADER)
+    /* Some formats want stream headers to be separate. */
+    if (oc->oformat->flags & AVFMT_GLOBALHEADER)
         c->flags |= CODEC_FLAG_GLOBAL_HEADER;
 
     return st;
@@ -264,26 +267,26 @@ static void open_video(AVFormatContext *oc, AVStream *st)
 
     video_outbuf = NULL;
     if (!(oc->oformat->flags & AVFMT_RAWPICTURE)) {
-        /* allocate output buffer */
-        /* XXX: API change will be done */
-        /* buffers passed into lav* can be allocated any way you prefer,
-           as long as they're aligned enough for the architecture, and
-           they're freed appropriately (such as using av_free for buffers
-           allocated with av_malloc) */
+        /* Allocate output buffer. */
+        /* XXX: API change will be done. */
+        /* Buffers passed into lav* can be allocated any way you prefer,
+         * as long as they're aligned enough for the architecture, and
+         * they're freed appropriately (such as using av_free for buffers
+         * allocated with av_malloc). */
         video_outbuf_size = 200000;
         video_outbuf      = av_malloc(video_outbuf_size);
     }
 
-    /* allocate the encoded raw picture */
+    /* Allocate the encoded raw picture. */
     picture = alloc_picture(c->pix_fmt, c->width, c->height);
     if (!picture) {
         fprintf(stderr, "Could not allocate picture\n");
         exit(1);
     }
 
-    /* if the output format is not YUV420P, then a temporary YUV420P
-       picture is needed too. It is then converted to the required
-       output format */
+    /* If the output format is not YUV420P, then a temporary YUV420P
+     * picture is needed too. It is then converted to the required
+     * output format. */
     tmp_picture = NULL;
     if (c->pix_fmt != PIX_FMT_YUV420P) {
         tmp_picture = alloc_picture(PIX_FMT_YUV420P, c->width, c->height);
@@ -294,23 +297,22 @@ static void open_video(AVFormatContext *oc, AVStream *st)
     }
 }
 
-/* prepare a dummy image */
-static void fill_yuv_image(AVFrame *pict, int frame_index, int width, int height)
+/* Prepare a dummy image. */
+static void fill_yuv_image(AVFrame *pict, int frame_index,
+                           int width, int height)
 {
     int x, y, i;
 
     i = frame_index;
 
     /* Y */
-    for(y=0;y<height;y++) {
-        for(x=0;x<width;x++) {
+    for (y = 0; y < height; y++)
+        for (x = 0; x < width; x++)
             pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
-        }
-    }
 
     /* Cb and Cr */
-    for(y=0;y<height/2;y++) {
-        for(x=0;x<width/2;x++) {
+    for (y = 0; y < height / 2; y++) {
+        for (x = 0; x < width / 2; x++) {
             pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
             pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
         }
@@ -326,13 +328,13 @@ static void write_video_frame(AVFormatContext *oc, AVStream *st)
     c = st->codec;
 
     if (frame_count >= STREAM_NB_FRAMES) {
-        /* no more frame to compress. The codec has a latency of a few
-           frames if using B frames, so we get the last frames by
-           passing the same picture again */
+        /* No more frames to compress. The codec has a latency of a few
+         * frames if using B-frames, so we get the last frames by
+         * passing the same picture again. */
     } else {
         if (c->pix_fmt != PIX_FMT_YUV420P) {
             /* as we only generate a YUV420P picture, we must convert it
-               to the codec pixel format if needed */
+             * to the codec pixel format if needed */
             if (img_convert_ctx == NULL) {
                 img_convert_ctx = sws_getContext(c->width, c->height,
                                                  PIX_FMT_YUV420P,
@@ -340,7 +342,8 @@ static void write_video_frame(AVFormatContext *oc, AVStream *st)
                                                  c->pix_fmt,
                                                  sws_flags, NULL, NULL, NULL);
                 if (img_convert_ctx == NULL) {
-                    fprintf(stderr, "Cannot initialize the conversion context\n");
+                    fprintf(stderr,
+                            "Cannot initialize the conversion context\n");
                     exit(1);
                 }
             }
@@ -352,36 +355,37 @@ static void write_video_frame(AVFormatContext *oc, AVStream *st)
         }
     }
 
-
     if (oc->oformat->flags & AVFMT_RAWPICTURE) {
-        /* raw video case. The API will change slightly in the near
-           futur for that */
+        /* Raw video case - the API will change slightly in the near
+         * future for that. */
         AVPacket pkt;
         av_init_packet(&pkt);
 
         pkt.flags        |= AV_PKT_FLAG_KEY;
-        pkt.stream_index= st->index;
-        pkt.data= (uint8_t *)picture;
-        pkt.size= sizeof(AVPicture);
+        pkt.stream_index  = st->index;
+        pkt.data          = (uint8_t *)picture;
+        pkt.size          = sizeof(AVPicture);
 
         ret = av_interleaved_write_frame(oc, &pkt);
     } else {
         /* encode the image */
-        out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture);
-        /* if zero size, it means the image was buffered */
+        out_size = avcodec_encode_video(c, video_outbuf,
+                                        video_outbuf_size, picture);
+        /* If size is zero, it means the image was buffered. */
         if (out_size > 0) {
             AVPacket pkt;
             av_init_packet(&pkt);
 
             if (c->coded_frame->pts != AV_NOPTS_VALUE)
-                pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base);
-            if(c->coded_frame->key_frame)
+                pkt.pts = av_rescale_q(c->coded_frame->pts,
+                                       c->time_base, st->time_base);
+            if (c->coded_frame->key_frame)
                 pkt.flags |= AV_PKT_FLAG_KEY;
-            pkt.stream_index= st->index;
-            pkt.data= video_outbuf;
-            pkt.size= out_size;
+            pkt.stream_index = st->index;
+            pkt.data         = video_outbuf;
+            pkt.size         = out_size;
 
-            /* write the compressed frame in the media file */
+            /* Write the compressed frame to the media file. */
             ret = av_interleaved_write_frame(oc, &pkt);
         } else {
             ret = 0;
@@ -418,7 +422,7 @@ int main(int argc, char **argv)
     double audio_pts, video_pts;
     int i;
 
-    /* initialize libavcodec, and register all codecs and formats */
+    /* Initialize libavcodec, and register all codecs and formats. */
     av_register_all();
 
     if (argc != 2) {
@@ -432,8 +436,7 @@ int main(int argc, char **argv)
 
     filename = argv[1];
 
-    /* auto detect the output format from the name. default is
-       mpeg. */
+    /* Autodetect the output format from the name. default is MPEG. */
     fmt = av_guess_format(NULL, filename, NULL);
     if (!fmt) {
         printf("Could not deduce output format from file extension: using MPEG.\n");
@@ -444,7 +447,7 @@ int main(int argc, char **argv)
         return 1;
     }
 
-    /* allocate the output media context */
+    /* Allocate the output media context. */
     oc = avformat_alloc_context();
     if (!oc) {
         fprintf(stderr, "Memory error\n");
@@ -453,8 +456,8 @@ int main(int argc, char **argv)
     oc->oformat = fmt;
     snprintf(oc->filename, sizeof(oc->filename), "%s", filename);
 
-    /* add the audio and video streams using the default format codecs
-       and initialize the codecs */
+    /* Add the audio and video streams using the default format codecs
+     * and initialize the codecs. */
     video_st = NULL;
     audio_st = NULL;
     if (fmt->video_codec != CODEC_ID_NONE) {
@@ -464,8 +467,8 @@ int main(int argc, char **argv)
         audio_st = add_audio_stream(oc, fmt->audio_codec);
     }
 
-    /* now that all the parameters are set, we can open the audio and
-       video codecs and allocate the necessary encode buffers */
+    /* Now that all the parameters are set, we can open the audio and
+     * video codecs and allocate the necessary encode buffers. */
     if (video_st)
         open_video(oc, video_st);
     if (audio_st)
@@ -481,18 +484,19 @@ int main(int argc, char **argv)
         }
     }
 
-    /* write the stream header, if any */
+    /* Write the stream header, if any. */
     avformat_write_header(oc, NULL);
 
-    for(;;) {
-        /* compute current audio and video time */
+    for (;;) {
+        /* Compute current audio and video time. */
         if (audio_st)
             audio_pts = (double)audio_st->pts.val * audio_st->time_base.num / audio_st->time_base.den;
         else
             audio_pts = 0.0;
 
         if (video_st)
-            video_pts = (double)video_st->pts.val * video_st->time_base.num / video_st->time_base.den;
+            video_pts = (double)video_st->pts.val * video_st->time_base.num /
+                        video_st->time_base.den;
         else
             video_pts = 0.0;
 
@@ -508,28 +512,27 @@ int main(int argc, char **argv)
         }
     }
 
-    /* write the trailer, if any.  the trailer must be written
-     * before you close the CodecContexts open when you wrote the
-     * header; otherwise write_trailer may try to use memory that
-     * was freed on av_codec_close() */
+    /* Write the trailer, if any. The trailer must be written before you
+     * close the CodecContexts open when you wrote the header; otherwise
+     * av_write_trailer() may try to use memory that was freed on
+     * av_codec_close(). */
     av_write_trailer(oc);
 
-    /* close each codec */
+    /* Close each codec. */
     if (video_st)
         close_video(oc, video_st);
     if (audio_st)
         close_audio(oc, audio_st);
 
-    /* free the streams */
-    for(i = 0; i < oc->nb_streams; i++) {
+    /* Free the streams. */
+    for (i = 0; i < oc->nb_streams; i++) {
         av_freep(&oc->streams[i]->codec);
         av_freep(&oc->streams[i]);
     }
 
-    if (!(fmt->flags & AVFMT_NOFILE)) {
-        /* close the output file */
+    if (!(fmt->flags & AVFMT_NOFILE))
+        /* Close the output file. */
         avio_close(oc->pb);
-    }
 
     /* free the stream */
     av_free(oc);