From 76e062322c3527b76b9b180ff0caa52b7af4784b Mon Sep 17 00:00:00 2001 From: Marton Balint Date: Sat, 11 Dec 2021 16:27:28 +0100 Subject: avformat/movenc: factorize data shifting And move data shift function from movenc to utils. Signed-off-by: Marton Balint --- libavformat/utils.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) (limited to 'libavformat/utils.c') diff --git a/libavformat/utils.c b/libavformat/utils.c index 332ba534d2..a78797ef57 100644 --- a/libavformat/utils.c +++ b/libavformat/utils.c @@ -2035,3 +2035,59 @@ const char *av_disposition_to_string(int disposition) return NULL; } + +int ff_format_shift_data(AVFormatContext *s, int64_t read_start, int shift_size) +{ + int ret; + int64_t pos, pos_end; + uint8_t *buf, *read_buf[2]; + int read_buf_id = 0; + int read_size[2]; + AVIOContext *read_pb; + + buf = av_malloc_array(shift_size, 2); + if (!buf) + return AVERROR(ENOMEM); + read_buf[0] = buf; + read_buf[1] = buf + shift_size; + + /* Shift the data: the AVIO context of the output can only be used for + * writing, so we re-open the same output, but for reading. It also avoids + * a read/seek/write/seek back and forth. */ + avio_flush(s->pb); + ret = s->io_open(s, &read_pb, s->url, AVIO_FLAG_READ, NULL); + if (ret < 0) { + av_log(s, AV_LOG_ERROR, "Unable to re-open %s output file for shifting data\n", s->url); + goto end; + } + + /* mark the end of the shift to up to the last data we wrote, and get ready + * for writing */ + pos_end = avio_tell(s->pb); + avio_seek(s->pb, read_start + shift_size, SEEK_SET); + + avio_seek(read_pb, read_start, SEEK_SET); + pos = avio_tell(read_pb); + +#define READ_BLOCK do { \ + read_size[read_buf_id] = avio_read(read_pb, read_buf[read_buf_id], shift_size); \ + read_buf_id ^= 1; \ +} while (0) + + /* shift data by chunk of at most shift_size */ + READ_BLOCK; + do { + int n; + READ_BLOCK; + n = read_size[read_buf_id]; + if (n <= 0) + break; + avio_write(s->pb, read_buf[read_buf_id], n); + pos += n; + } while (pos < pos_end); + ff_format_io_close(s, &read_pb); + +end: + av_free(buf); + return ret; +} -- cgit v1.2.1